It involves prefixing a verb form with the letter waw in order to change its tense or aspect.
The prefix conjugation in Biblical Hebrew normally indicates non-past tense or imperfective aspect.
Although always appearing in unpointed texts as a simple vav, it has various pronunciations depending on meaning and phonetic context.
Example: The origin of this construction is usually placed in a shift in the meanings of certain verbal forms between Proto-Semitic and the Central Semitic languages.
First, the preterite */yaqtul/ and the imperfect */yaqtulu/ coalesced in Hebrew into a single verbal form, because of the loss of final short vowels.
The non-past "/wǝ-/ + suffix-conjugation" was created by analogy, quite possibly influenced by the survival of the suffix conjugation as a stative form with nonspecific tense.
G. R. Driver writes:[3] "All attempts to explain this at first sight strange phenomenon, whereby two tenses apparently exchange functions, on logical grounds, have failed, but the historical development of the Hebrew language readily accounts for it.
Vav-consecutive is attested in other Northwest Semitic languages as well: with imperfect, in Moabite, in Deir Alla Inscription, and in Aramaic; and with perfect in conditional clauses, in Ugaritic, in Amarna letters, and in Phoenician.
The Lachish letters, dating to c. 590 BC, have only a single occurrence of vav-consecutive; in all other cases, the perfect form is used to describe events in the past.