Three kinds of words: ism, fiʿl, ḥarf

Every Arabic word is one of three kinds: ism (a name or noun), fiʿl (an action or verb) or ḥarf (a particle).

Ism — the name of a person, thing, place or quality. For example: book, mercy.

Fiʿl — an action tied to a time. For example: he said, he created.

Ḥarf — a word that does not give full meaning alone but links other words. For example: in, from, on.