One of the most important character in persian calligraphy is zero-width non-joiners. This character is used when one word contain two part that shouldn’t connected into a ligature.

For example when writing certain prefixes, suffixes and compound words we prevent letter from joining the following one but without adding a space between the two.

When ZWNJ placed between two characters causes them to be printed in their final and initial forms, respectively. The HTML entity for this character is ‌ .

html result description
آن ها آن ها wrong because this is a compound word not two septrace one
آنها آنها wrong because in persian calligraphy this word must write septrately
آن‌ها آن‌ها correct