What ّ means
It doubles the consonant, not the vowel. In دَرَسَ, ‘he studied,’ the middle consonant is single; in دَرَّسَ, ‘he taught,’ it is doubled. Read the shadda with the letter beneath it, not the next letter. In writing that otherwise omits pronunciation marks, adding it can clarify which word you mean.
Where did the shadda come from?
It developed within Arabic’s tradition of marking pronunciation. Early colored dots guided vowels and recitation; Arabic vowel dots appear in 675–725 CE. That dates the broader tradition, not this particular sign. Grammatical accounts associate letter-shaped marks with the scholar al-Khalil; later writers describe shadda as a reduced form of shin, an Arabic letter. The modern mark specifically indicates consonant doubling.
How do I type the shadda?
Type the consonant first, then the shadda. Look for the small w-shaped mark above that letter. When combined with kasra, the short i vowel mark, its arrangement depends on the font: kasra may sit below the letter or between it and shadda. If the marks collide, try another Arabic-capable font.
A pronunciation mark in Arabic writing, not an emoji reaction.
Adding shadda can change the word, not just its appearance.
Don't confuse it with
2Combination ideas
3Questions people ask
1Why does ّ show as a box on some devices?
Because that device's fonts have no glyph for it. The character is still correct and still copies correctly — the box is a missing glyph, not a broken character.
How to type ّ
ّ\0651Codes and encoding1 code points
A visible symbol can contain several code points. JS .length counts UTF-16 units; UTF-8 counts bytes.