Ism, fiʿl, ḥarf: the three word types
Arabic · Key Stage 3 · The School
Only three kinds of word
Classical Arabic grammar sorts every word into just three types. Ism: a naming word — people, places, things, ideas (كِتاب، مَدْرَسة). Fiʿl: an action word carrying time — past, present or command (كَتَبَ، يَكْتُبُ، اُكْتُبْ). Ḥarf: a small particle that only means something with other words — في (in), مِن (from), وَ (and). Every sentence you will ever read is built from these three.
Al-: the definite article
ال at the front of a noun means "the": كِتاب (a book) → الكِتاب (the book). It glues onto the noun as one word. After ال, a noun never carries tanween — Arabic never says "the a book". This one rule instantly explains thousands of word endings you will meet.
Sun and moon letters
With half the alphabet — the "sun letters" like ش س ن ر — the lām of ال goes silent and the next letter doubles: الشَّمْس reads "ash-shams", not "al-shams". With "moon letters" like ق م ك, the lām is pronounced: القَمَر reads "al-qamar". The writing never changes; only the sound does. Listen for it in recitation: it is everywhere.
Take إِنَّ اللهَ مَعَ الصّابِرين. إِنَّ is a ḥarf — a particle, it cannot take ال or tanwīn and has no tense. اللهَ is an ism. مَعَ is a ḥarf. الصّابِرين is an ism. No verb at all in this one, which is exactly why it is a nominal sentence. Test each word: can it take ال? Does it have a tense? If neither, it is a ḥarf.