Bitter is a type of ale, originally derived from pale ale. A stronger version has become a popular bottled beer. The main ingredient is malted barley, with hops only added to improve the keeping properties and give a distinctive smell and taste.

Bitter covers a wide variety of taste, aroma and appearance. These include copper, malty, dry and sweet, while some have the aroma of hops. In Yorkshire the bitter tends to have a creamy head, whilst in the South East England the beer is generally more hoppy and served without a head.

In Scotland Bitter is commonly referred to as "heavy"; as in "A pint of heavy".

Brewers in England include (see also Category:English breweries):

• Abbeydale Brewery of Abbeydale , Sheffield
• Adnams
• Arkells
• Bank's
• Beards of Sussex of Herstmonceux
• Brakspears
• Eldridge Pope
• Everards of Narborough, Leicestershire
• Fuller's of Chiswick, London
• Gales Ales
• Greene King of Bury St Edmunds
• Hall and Woodhouse
• Harveys of Lewes, East Sussex.
• Hogs Back Brewery , Surrey
• Kelham Island Brewery of Sheffield
• Mansfield Brewery
• Marstons
• Shepherd Neame of Faversham, Kent – allegedly Britain's oldest brewery
• Ringwood Brewery
• Samuel Smiths
• Tetley's
• Theakston's
• Titanic Brewery of Burslem, Stoke-on-Trent
• Whitbread including Brickwoods and many others
• Youngs of Wandsworth, London

A good source of information is The Campaign for Real Ale (CAMRA) in the UK, and the beer information page of RateBeer: http://www.ratebeer.com/Beer.asp. Bitter beer is produced in other countries, but is less popular than Lager beer or Stout beer (an example of which is Guinness). In particular, consumers in the United States show very little demand for bitter beer; advertisements for a brand of lager beer bill the product as a "never bitter beer".

Several popular Australian lagers are branded "bitter" (notably Victoria Bitter) to the derision of visiting Britons.