Lunar letters are the letters which make you pronounce the ل in ال. For example, we say "al-qamar" (=the moon), but we don't say "al-shams" (=the sun). Instead, we say "asshams". That's why they are called lunar and solar letters. Lunar letters are gathered in the following sentence: ابغ حجك وخف عقيمه All the other letters are solar letters. For example, we say "assalamu alaikum" not "al salamu alaikum". Another examples: النور =annoor السيارة =assaiyara الولد =al walad البنت =al bent الرجل =arragol If you want more examples, let me know :) Hope this helps.

What you are trying to understand, is what we call in arabic "الام الشمسية و الام القمرية". To define words in arabic we use "ال" which means "The" Example: ولد : A boy الولد : The boy There are two cases: When the letter "ل" = "Laَm" is not spelt, we call it "الام الشمسية" = "Sun Laَm" When it is spelt we call it "الام القمرية" "Moon Laَm" So the question is when the letter "ل" is spelt and when it is not. Rule 1: In arabic, the letter "ل" is not spelt when follwed by the these letters (Sun Letters) : ت, ث, د, ذ, ر,ز, س, ش, ص, ض, ط, ظ, ل,ن. ُُExample : سيف (Sayfon) : A sword السيف (As-sayfu) : The sword Important: Notice that the letter "ل" is not spelt but the letter "س" is spelt with emphasis, it is what we call in arabic "إدغام" Rule 2: The letter "ل" is spelt when is it followed by these letters (Moon letters): .أ, ب, ج, ح, خ, ع, غ, ف,ق, ك, م, ه,و,ي Example: كتاب "Kitaَbon" : A book الكتاب "Al-Kitَbu" : The book Important: Notice that the letter "ل" is spelt without using any vowel, and the the letter "ك" keeps its original sound To better understand the concept you need to hear some examples. I hope i have made myself clear Good luck