Tank classification can be done in a variety of ways: usually either by intended role, or by weight.

The most common division in role has been between tanks intended to focus on fighting against infantry, and tanks intended for fighting against other AFVs, especially other tanks.

Weight-based classifications are useful, but only in reference to a period's other tanks (for example, a light tank at the end of World War II would have been considered a heavy tank at the beginning). Light, medium, and heavy have other meanings than just weight, e.g., relating to gun size, the amount of armour, or speed.

As an example, in the mid 1930s to early '40s, Germany developed a new generation of combat tanks after the Panzer I. It resulted in the 'medium' Panzer III, armed with a anti-tank gun and intended to engage tanks, and the 'heavy', 'infantry support' Panzer IV, initially armed with a 75 mm short-barrelled gun for engaging infantry. The differentiation was not absolute: the IV could fire HEAT shells and the III could fire high-explosive shells to attack infantry, but neither was as effective in the roles of the other. By the start of World War II, the Pz IV would be a medium and the III light medium, when compared to French tanks of the time.

Note that the meaning of general type name like 'light tank' can describe different types of vehicles in different periods or among different countries.

Classification of tanks

Classifying tanks across the almost 100 years of their existence is not hard when the original classification is used. However, to come up with a classification that works across period is difficult. Classifications have meant different things to different countries, and have changed over the year. To understand how a tank design is classified overall, the specifications and role the tank was designed to, and period this was done in must must be understood as well.

Tanks are often referred to by weight-based classification, such as 'light', 'medium' or heavy'. Many types are also described by their tactical role, which depends on contemporary military doctrine. For instance 'cruiser' and 'infantry' tanks are British classifications of the 1930s and '40s; 'breakthrough' and 'fast' are contemporaneous Soviet types. 'Light', 'Medium' and 'Heavy' tank descriptions also imply tactical roles. Furthermore, expected weights for a given tank type vary over time; a medium tank of 1939 could weigh less than a light tank of 1945. The British Matilda infantry tank weighed as much as a German Panzer III or Panzer IV medium tank, but due its heavy armour had some of the traits of a heavy tank.

Overview

Some of the names developed for tracked AFV and tank types over history

• Up to 1918
  • 'male', 'female'; light tank, medium tank, heavy tank
• 1918 to 1950
  • tankette, armoured reconnaissance, armoured combat, combat car, tank destroyer, fast tank, cruiser tank, cavalry tank, assault tank, infantry tank.
• 1950-2005
  • main battle tank, infantry fighting vehicle, Boyevaya Mashina Pekhota (BMP, infantry fighting vehicle), Stridsfordon ("Combat Vehicle")

Tank types

There were many names given to different tank types, and similar names do not assure the same design goals. Some light tanks were relatively slow, and some were fast. Some heavy tanks had large-calibre low-velocity guns for engaging infantry and bunkers, and some had high-velocity antitank guns.

WWI Tank Types

In WWI the first tank, the Mark I, was designed for breaking through trenches supporting infantry. Initially, there were two types with two roles. The 'males' armed with artillery guns, and 'females' armed with machine guns to protect the 'males' from infantry. The tanks that followed were described relative to it, including light, medium, and super-heavy tanks. For example, the light tank FT-17 (weight approximately 7t / 15,000 lb.) and the medium Medium Mark A 'Whippet' (14t / 31,360 lb.). By the end of the war, the Mark I (~30 t / 56-60,000 lb.) could be classified as a medium tank, and the Whippet as a light tank. Super-heavy breakthrough tanks such as the Char 2c (60t / 138,000 lb.) were completed before the war ended, but did not see combat. In comparison, the current British MBT, the Challenger 2, weighs some 60t (137,500 lb).

Tankette

A tankette was a term for a small tank, with a crew of 1-2 similar in form to WWI-era light tanks, but faster. They often had no turret, or if it did, it was traversed by hand. It was armed with 1 or 2 machine guns, or rarely with a small calibre cannon. A classic design was British Carden-Loyd Mk.VI Tankette - many others were modelled after it. Tankettes were produced between about 1930 and 1939, but production ceased soon afterwards due to limited usefulness and extreme vulnerability against Anti-tank weapons. The role of tankettes, mainly scouting and some anti-infantry fighting, were largely taken over by armoured cars, and the terms has fallen out use as well.

There are some relative small AFVs, but they are only somewhat similar, and use other terms such as Infantry fighting vehicle. The Wiesel1 IFV for example, is called a weapons carrier as rather then having a narrow role like tankettes had, its used for variety of roles.

The French Armoured Reconnaissance type of the 1930s (Automitrailleuses de Reconnaissance) was essentially a tankette in form, but specifically intended for doing reconnaissance.

The Japenese were among the most prolific users of tankettes, producing a number of designs, which they found useful for jungle warfare.

Light tank

Light tanks tended to be smaller, lighter, vehicles. In practice they were often just the previous generation of medium tanks that had been re-classified, and not actually specifically designed. For example, the M24 Chaffee was a purpose built light tank of late WWII, but weighed more then the Panzer III, a medium at the start of the war. They were quite common at the start of World War II, and remained so but they were relegated to use as scouts or minor fighting. Many were amphibious, and some, like the Tetrarch were small enough to be air-lifted to the battlefield. They were often preferred over armoured cars for scouting.

After WWII light tanks continued in the reconnaissance role for some time thanks to their modest cost and potential for amphibious capabilities, but have been eventually replaced by infantry carriers and armoured cars.

The French WWII-era Light Tank (Char Léger) type was generally similar to other nations' light tanks of the period. Since it was intended to be used for infantry support rather than scouting, it was slower than most light tanks intended for this role. The French intended the Armoured Reconnaissance (Automitrailleuses de Reconnaissance) and Armoured Combat (Automitrailleuses de Combat) for the scouting and light combat role.

Fast tank

The fast tank (Bistrokhodniy Tank) classification was given to the BT series of tanks by the USSR. Fast tanks differed from Soviet light tanks by an emphasis on speed, and descended from a Christie tank prototype of the early in 1930s. The T-34 mediums were a development of this line of tanks as well, though they would be classified as mediums instead.

The French Armoured Combat type (Automitrailleuses de Combat) was a lighter tank compared to other classes. Its design sacrificed speed for armour, but had similar armament and was similar to the fast tank type.

Medium tank

Medium tanks were neither the heaviest nor lightest in the arsenal, and many of the designs had successful balance of firepower, mobility, protection, and endurance and could often be adapted to a variety of roles. In WWI, the first tank, the Mark I turned out to be a 'medium' tank being about in the middle of lighter and heavier designs of the time. In the intra-war period a medium tank would probably be something like the T-28, though tanks 7TP or LT-38 could also be considered.

There were medium tanks that focused anti-infantry, such as in WWII the Panzer IV short-barrel and the Sherman with a 75 mm gun, and medium tanks that were more focused on the anti-tank role, such as the later versions of both those tanks and T-34s.

The French Medium Tanks (Chars Moyens) were much the same as their light tanks, but of a heavier sort and intended for infantry support. Their Cavalry Tanks (Chars de Cavalerie) focused on speed in addition to power and protection of the other designs. They were similar to what other countries called medium tanks, but were specifically intended for what is now considered the MBT role.

In modern times, the MBT is largely descendent of the faster medium-sized tank designs of WWII, especially the cruiser, cavalry, and anti-tank–focused medium tanks. Heavy tanks are no longer significantly used, having fallen out of use in the 1960s. This means that the lighter-class vehicles including older generations of MBTs, or other hybrid vehicles such as the M2 Bradley, function in the medium tank role.

Heavy tank

Heavy tanks have usually been deployed to fulfil the need for a breakthrough tank, though in practice have been more useful in the defensive role then in the attack. Design goals have included attacking obstacles, creating breakthroughs, and engaging enemy armoured formations. They feature very heavy armour and guns relative to lighter tanks, however they tend to push power plants to the limits. As a result they tend to be either underpowered and comparatively slow, or have engine and drive train problems from overworking the engine.

The first tank, the Mark I of WWI was designed around this philosophy, even more so the Char 2c one of the largest tanks ever produced. At the start of WWII the Soviets and French were the only countries to have inventories of what for time were heavy tanks by weight, such as the T-35. The Matilda II, though not as heavy as the others had thicker armour then any tank in service at the time. Later war examples were the German Tiger I and II, as well as the Soviet KV series and the IS series, and to a degree, even the Sherman Jumbo . Heavy tanks achieved their greatest success holding off larger numbers of attacking lighter tanks.

After WWII came the last major fielding of heavy tanks in addition to mediums, which included the M103 heavy tank, the FV214 Conqueror, and ARL-44 in response to the IS-3s. After these, what had been medium tanks then became the largest tanks, and came to be known as Main Battle Tanks (MBTs), with no specialised super-heavy tanks being fielded.

The value of heavy tanks was destroyed by large HEAT guided missiles, and HEAT rounds which rendered heavy tanks ineffective in stand-off situation. Before, heavy tanks' greater expense and lower mobility was countered by greater survivability and ability to survive when ambushing, but advances in projectile technology rendered this more-or-less futile and higher survivability would have to be attained through other aspects of the design.

Cruiser tank

A Cruiser tank is a tank that is designed to move fast and destroy enemy tanks. The idea came from the concept of "Fast Tanks" pioneered by Walter Christie .

They were used by the United Kingdom during World War II, and were typically thinly armoured and armed with anti-tank guns that could not effectively combat infantry or towed anti-tank weaponry. Cruiser tanks were designed to complement infantry tanks, exploiting gains made by the latter to break through enemy lines and assault from the rear. In practice they largely proved to be less effective than the German tanks they opposed.

The early Cruiser tanks (marks A9 and A10) were comparatively lightly armoured, but mobile and reasonably well-armoured for the early campaigns of WWII. Earlier cruiser tanks were largely replaced by larger cruisers such as the Crusader series, though in some cases reverted to even lighter scouting tanks such as the U.S. M3 Stuart (referred to by its crews as the 'Honey'). In 1942–1944, British cruiser tank units were re-equipped with American M4 Sherman tanks. In 1944 they were partially converted back to British-made Cromwell cruiser tanks which were much faster than the Sherman but more lightly armoured. The final cruiser tank was the Comet, introduced in late 1944, which was an extremely effective medium tank on, a par with the German Panther.

Infantry tank

The idea for this tank was developed during World War I by the British and French. The infantry tank was designed to work in concert with infantry, moving at a running pace, which let it carry much heavier armour than the average tank. Its main purpose would have been to clear the battlefield of obstacles, kill enemy soldiers, and protect the infantry on their advance into and through enemy lines.

One of the best-known infantry tanks was the Matilda II of World War II. Its armour was thick enough to stop all but the most powerful anti-tank rounds of the period. Its 2 pounder gun was sufficient to take on most light and medium tanks of the early war. It shold not be confused with the infantry Tank Mk 1 Matilda, also an infantry tank, which was armed with only a machine gun. The Churchill and Valentine Infantry tanks were also successful models, each with a number of variants, such as ones mounting heavier guns like the 6-pounder .

Specialist tanks

M1A1 with mine plough

Tanks have often been modified for special purposes. Often they provide armoured capability for combat engineers. These include tanks with large-calibre demolition guns, with flails or ploughs for mine-clearing, bridge-layer tanks, or flame tanks armed with flame-throwers.

Another common modification is the amphibious tank, such as the Sherman Duplex Drive (or DD). These designs are modified with waterproofing and propulsion systems to be able to traverse open water. Their most notable usage was on D-Day.

An example would be the Churchill AVRE, intended for destroying bunkers, amphibious tanks, and mine-clearing tanks.

Many of the specialist tank roles have been spun off to other vehicle types that are no longer called tanks, though many tank chassis give rise to wide variety of vehicles ranging from AA to bridge layers. Also, there exists many attachments to allow tank to certain special task, especially mine clearing devices.

Main battle tank

Advances in tank design, armour, and engine technology allowed tank designers to increase the capabilities of tanks significantly without always resorting to heavier designs, although weights did gradually increase. However, HEAT ammunition was a huge threat to tanks and could penetrate steel armour thicker then was practical to put on a tank. Advances such as Chobham armour did much to limit the effectiveness of weaker HEAT rounds, but the vulnerability has remained. The demise of the heavy tank meant that what had been medium sized vehicles were now the heaviest. What remained were developments of the more heavy-set cruiser tanks of Britain, and medium tanks intended for anti-tank work of other nations, but with a focus on weapon power and mobility greater then ever before. The name Main Battle Tank gained widespread use.

The term Main Battle Tank is applied to tanks designed to function as the backbone of modern ground forces. It is armed and armoured to face as many kinds of threat as possible, but especially direct hits from other tanks and lighter infantry anti-tank weapons. However, the threats to MBTs on a modern battlefield are numerous.

Even heavily armoured MBTs are vulnerable to all manner of anti-tank weapons, often designed to attack the most vulnerable locations: the top, the bottom, and the tracks. Tanks also retain much of their vulnerability to artillery fire and mines. While a tank can afford to have half a metre of armour on the front, it can't have it everywhere.

The solution was to focus on the traits that allow the tank to survive: mobility and firepower. The amount of armour added was usually sufficient to stop at least previous-generation projectiles from penetrating. Armour on the more advanced MBTs has been shown to deflect older generation projectiles, but there is little public information on the armour levels of the latest MBTs, as such information is generally kept secret. Some of the known examples are from friendly fire. For example, in the Gulf War in 1991, it was shown that a U.S. Hellfire anti-tank missile could destroy an M1 Abrams.

Other types of AFVs

For an armoured unit to fulfil its various assigned taskings (supporting infantry in the assault, heavy reconnaissance, etc.), They require specialised equipment supporting these characteristics, e.g., fire control,communications (between and within vehicles), deep fording equipment, stand-off or composite armour, etc. Tank crews require the training and drills to fight within a tank unit and operate and maintain their equipment. Tank operations have huge logistical requirements, requiring a high level of maintenance, fuelling, and supply. These role have often been filled by tanks, or other tracked armored vehickes derived from tanks, in addition to other types. However, they are often called by a different designation. This is especially true for tracked, armoured vehicles intended for indirect-fire, assault guns and for anti-tank vehicles.

Tank destroyers

Tank destroyers is a vehicle intended to destroy tanks and encompasses wide range of types. Tank destroyers are usually considered separately from regular tanks, because although some may look like tanks they have different traits and design goals, especially relative to other vehicles of a era. In the scheme of the history of tank they can in many cases abide by most, if not all of the qualifications of tank, but just not relative to other tanks of the day. There is no one vehicle type that is a tank destroyer, there are similar only through their role. They may be be very slow and heavily armoured, or very fast and lightly armoured, or wheeled or tracked. They do generally sacrifice some major component that is common to a regular tank's design, and in particular, they tend to sacrifice versatility.

Forces have many times attempted to put more effective units into battle by employing self-propelled anti-tank guns, or tank destroyers, in some of the roles of tanks. These AFVs are designed for ambush, or hit-and-run attacks on tanks and other armoured vehicles.

Around the WW2 period their were a few main types used. The Czech, German and Soviet destroyers focused mainly on increasing firepower, armour, reducing height, but they did away with a revolving turret which made them more vulnerable to flanking, especially in attacks (Such as the ISU-122. Another type used especially by the Germans, was to mount a AT gun without a turret on a tracked chassis, but with only thin armour and exposed crew (such as the Panzerjager I).

Another type looked very much like tanks with powerful guns and revolving turrets, but did not have nearly as much armour as a similarly sized tank of the day, and many were open-topped, as well. These are also sometimes known as known as self propelled guns, or SPAT for self propelled anti-tank. The designs sacrificed armour for mobility and firepower, which, in theory, works in pure tank vs. tank combat, given certain conditions. However, the battlefields were mixed, and tank destroyers were vulnerable not just to tanks, but many lighter-calibre guns, and the open-topped ones to shell-burst and grenades as well.

There were other types of tank destroyers as well, such as portées and wheeled ones. The Stryker for example, has a anti-tank variant with a 105 mm anti-tank gun.

Assault guns and Self-propelled artillery

Various types of artillery pieces have been given their own integral transport by mounting them on an armoured, tracked or wheeled chassis. This lets them keep up with the pace of armoured warfare, and gives them nominal protection from counter-battery or small arms fire. Like towed artillery, a battery of self-propelled guns must still set up in a relatively safe area to perform fire missions.

There have been a number of designs that mount artillery pieces, such howitzers and mortars, but are intended to function in the direct-fire role, especially for infantry. These are often called assault gun, though they have been equipped with ant-tank guns essentially turning them into tank-destroyers. One of the most prolific of this type was the WWII era Stug .

Infantry fighting vehicles

IFVs are armed infantry carriers, used to describe a range of vehicles sizes and types, with varying levels of anti-AFV and anti-tank capability (various examples mount autocannons, smoothbore gun/missile systems, or ATGMs), and firing ports , allowing the mounted infantry soldiers to use their personal weapons from within the vehicle.

The first purpose designed tracked APC, that was also a tank was invented by the British in WWI, a Mark V type that could house a squad of infantry but was also armed as a tank. The idea was largely dropped in favour of armoured trucks and half-tracks, which were were used for transporting infantry up to and during WWII. They were usually comparatively thinly armoured and barely armed compared to tanks. During WW2 there were some experiments into heavily armoured carriers, such as the Ram APC , based on a tank but only equipped with a machine gun. There was a shift away from half-tracks later, with either tracked or wheeled APC (essentially roomy armoured cars) for the APC role. They were also armed to varying degrees.

Combinations of the APC with various anti-vehicle or infantry support weapons have come to be known as Infantry Fighting Vehicles. From 1960s , IFVs started to compliment and then replace unarmed armoured personnel carriers. IFVs are intended to be more useful in combat, carrying and supporting infantry rather than acting as simple "battle-taxis". In many cases, such as the BMP-1 or BMD, they have taken on the reconnaissance and air-mobility roles of light tanks. Heavier designs have also taken on some of the anti-tank capability of tanks, such as the case of the M3 Bradley. By comparison the Israeli Merkava is a MBT with the ability to carry a section of infantry.

Wheeled APCs, which never entirely disappeared are also starting to be more heavily armed and function as IFVs.

See also

• Comparison of early World War II tanks
• Tank history
• Hull-down