One way to paradise

All articles In Arabic are indeclinable without any exception.
We cannot study all the Arabic articles in one lesson; rather we will learn each type of article in its own grammatical topic and lesson. Here we will gain a general idea about how they are indeclinable.
There is no rule for the vowel ending on which the article is indeclinable (some of them are indeclinable on fatħah, others on sukūn, others on long vowel, etc.) Therefore you have to memorize the vowel ending of each new article you learn. The following table contains some examples of each type of article and their sign of indeclension:

Category	Sign of indeclension	Meaning	Article
Preposition حَرْفُ جَرٍّ	Sukūn	From	مِنْ
	Sukūn	About	عَنْ
	Sukūn of long vowel	To	إلَى
	Sukūn of long vowel	On	عَلَى
	Sukūn of long vowel	In	فِي
	Kasrah	With	بِـ
	Kasrah	For	لِـ
Coordinating articles حَرْفُ عَطْفٍ	Fatħah	And	وَ
	Sukun	Or	أَوْ
	Sukun	Rather, but	بَلْ
	Sukun	But	لَكِنْ
Annular article (sisters of /inna/) حَرْفٌ نَاسِخٌ	Fatħah	Indeed	إنَّ
	Fatħah	If only! (Would that!)	لَيتَ
	Fatħah	But	لَكِنَّ
	Fatħah	I hope (it is hoped)	لَعَلَّ
Interrogative Article حَرْفُ اسْتِفْهَامٍ	Sukun	Is…?	هَلْ؟
Interrogative Article حَرْفُ اسْتِفْهَامٍ	Fatħah	Is…?	أَ؟
Conditional article حَرْفُ شَرْطٍ	Sukūn	If	لَوْ
Conditional article حَرْفُ شَرْطٍ	Sukūn	If	إنْ
Accusative article حَرْفُ نَصْبٍ	Sukūn	To	أَنْ
Accusative article حَرْفُ نَصْبٍ	Sukūn	Will not	لَنْ
Jussive article حَرْفُ جَزْمٍ	Sukūn	Did not	لَمْ
Answering article حَرْفُ جَوَابٍ	Sukūn	Yes	نَعَمْ
Negating article حرْفُ نَفْيٍ	Sukūn of long vowel	No	لا

N.B.: Exceptionally, the vowel ending of some articles may change when followed by a sukūn on the first letter of the following word as in the following examples:

Note	Example
Note	English	Arabic
The vowel ending of /minn/ is changed from sukūn into fatħah, because the following sound is sukūn	From home	مِنَ الْبَيْتِ
The vowel ending of /ξann/ is changed from sukūn into kasrah, because the following sound is sukūn	About the moon	عَنِ الْقَمَرِ
The vowel ending of /Aw/ is changed from sukūn into kasrah, because the following sound is sukūn	The night or the day	اللَّيلُ أَوِ النَّهارُ
The vowel ending of /hal/ is changed from sukūn into kasrah, because the following sound is sukūn	Is the square far?	هَلِ الْمَيْدَانُ بَعِيدٌ؟

In the above mentioned examples the articles are indeclinable with virtual signs which were found on the single article before the structure and the vowel ending is changed (for phonetic reasons).