There are several prefixes in the Hebrew language which are appended to regular words to introduce a new meaning. In Hebrew, the letters which form these prefixes are called "formative letters" (Hebrew: אוֹתִיּוֹת הַשִּׁמּוּשׁ, Otiyot HaShimush). Eleven of the twenty-two letters of the Hebrew alphabet are considered Otiyot HaShimush. These letters are Aleph (א), Bet (ב), He (ה), Vav (ו), Yud (י), Kaf (כ), Lamed (ל), Mem (מ), Nun (נ), Shin (ש), and Tav (ת). A mnemonic to remember these letters is "Eitan, Moshe, v'Kalev" (Hebrew: אית"ן מש"ה וכל"ב) which translates to "Eitan, Moshe, and Caleb."
Prefixes in Hebrew serve multiple purposes. A prefix can serve as a conjunction, preposition, definite article, or interrogative. Prefixes are also used when conjugating verbs in the future tense and for various other purposes.