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 read the word; اِنّ it is actually spelled 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.
Now let’s read another words.
