Shadda 
The Shadda ( ﹼ ) indicates the doubling of a consonant. Shadda is formed by bringing together two of the same letter: The first one is with sukoon and the second one with a vowel.
For example when we type the word; اِنّ it is actually spelt as this اِنْ نَ
The two Noon’s have come right next to each other. The first is with Sukoon and the second with a short vowel, so they are written as one noon with a Shadda above.
Let’s discuss other examples below.
