Verb-second (V2) word order, in syntax, is the effect that in some languages the second constituent of declarative main clauses is always a verb, while this is not necessarily the case in other types of clauses.

V2 effect

The V2 effect is clearly demonstrated in the following Dutch sentences:

Ik las  gisteren  dit  boek.
I  read yesterday this book
"Yesterday I read this book."

Gisteren  las  ik dit  boek.
yesterday read I  this book
"Yesterday I read this book."

Dit  boek las  ik gisteren.
this book read I  yesterday
"Yesterday I read this book."

It may seem that the verb is in the third position in the last sentence, but it is the second constituent; the first constituent is "dit boek" (this book).

Note the contrast with the following embedded clauses:

het boek, dat  ik gisteren  las
the book, that I  yesterday read
"the book I read yesterday"

ik zei  dat  ik gisteren  dit  boek las
I  said that I  yesterday this book read
"I said I read this book yesterday."

Similar examples can be given for German.

The usual analysis of the Dutch (and German) V2 phenomenon is that the "normal" position of the verb is at the end of the clause (SOV) and that in main clauses, the inflected verb moves to the second position. This is supported by the fact that in sentences with verb clusters, only the auxiliary appears in the second position:

Ik heb  dit  boek gelezen.
I  have this book read
"I've read this book."

Ik heb  dit  boek willen lezen.
I  have this book want   read
"I've wanted to read this book."

Ik heb  dit  boek willen kunnen lezen.
I  have this book want   can    read
"I've wanted to be able to read this book."

Classification

V2 word order is primarily associated with Germanic languages, English being a notable exception. (French, a Romance language had a V2 stage, and Kashmiri currently does.) Other verbs are placed in the position dictated by the prevailing word order of the language: in otherwise SVO languages, such as Swedish and Icelandic, the verb is placed after the subject but before the object; in otherwise SOV languages, such as German and Dutch, the verb is placed after the object.

In addition, there are two prime distinctions of V2 languages. The CP-V2 languages such as Swedish and German only allow the movement in main clauses. On the other hand, the IP-V2 languages such as Icelandic and Yiddish require movement in subclauses too. (The CP and IP refer to a particular theory of grammar in which there is a position known as the complementizer, to which the verb moves in CP-V2 languages. Finding it already occupied by the complementizer pronoun 'that' in subclauses, movement is prohibited. On the other hand, in IP languages, a position known as I is found directly after the C position, which is never occupied (except after V2 movement) and thus movement is allowed in subclauses. Although this theory is explained with reference to a particular theory, the difference between Swedish and German grammar on the one hand and Icelandic and Yiddish grammar on the other is real, and the terms 'CP-V2' and 'IP-V2' are used even by those who do not subscribe to the theory.)

An earlier stage of English was V2, and some vestiges of its former structure have remained: fixed phrases such as 'so am I' and productive structures like 'I didn't go and neither did he', with the verb before the subject ('I' and 'he', respectively). As with all verb movement in Modern English, only modal verbs can move, and so the dummy do is added when necessary. It has been argued that older English word order was of the SVO, IP-V2 sort, and it is easy to see how such an order can with little change develop into a simple SVO language as is Modern English today.

The following examples of word orders use English words.

CP-V2, SOV

ex. German, Dutch
I read the book yesterday.
Yesterday did I the book read.
You know that I the book yesterday read.
You know that yesterday I the book read.

CP-V2, SVO

ex. Swedish
I read the book yesterday.
Yesterday did I read the book.
You know that I read the book yesterday.
You know that yesterday I read the book.

IP-V2, SOV

ex. Yiddish
I read the book yesterday.
Yesterday did I the book read.
You know that I the book yesterday read.
You know that yesterday did I the book read.

IP-V2, SVO

ex. Icelandic
I read the book yesterday.
Yesterday did I read the book.
You know that I read the book yesterday.
You know that yesterday did I read the book.