Izhar (الإِظْهَار) means making clear; technically it is pronouncing the silent Nun or the Tanwin from its makhraj, with no added Ghunnah, when a throat letter follows. Its six letters are Huruf al-Halq (حُرُوف الحَلْق): Hamzah, Ha', 'Ayn, Ha', Ghayn and Kha'. The reason is the distance between the makhraj of Nun and these letters. With Nun it occurs within one word or across two; with Tanwin only across two.
Izhar Halqi
مَنۡ ءَامَنَمَنْ اٰمَنَ
Al-Baqarah 2:62
يَنۡهَوۡنَيَنْهَوْنَ
Al-An'am 6:26
مِنۡ عِلۡمٍمِنْ عِلْمٍ
An-Nisa 4:157
مِنۡ حَكِيمٍ حَمِيدٖمِنْ حَكِيْمٍ حَمِيْدٍ
Fussilat 41:42
مِنۡ غِلّٖمِنْ غِلٍّ
Al-A'raf 7:43
مَّنۡ خَشِيَمَنْ خَشِيَ
Qaf 50:33
عَذَابٌ عَظِيمٞعَذَابٌ عَظِيْمٌ
Al-Baqarah 2:7
Tanwin before 'Ayn
أَنۡعَمۡتَاَنْعَمْتَ
Al-Fatihah 1:7
مِنۡهُمۡمِنْهُمْ
Al-Baqarah 2:75
Note
Its sign in the Madinah Mushaf: a sukun on the Nun, and the two marks of Tanwin placed directly one above the other.Note
In the Indo-Pak Mushaf the silent Nun always carries a sukun (jazm); Izhar is recognised by the next letter being a throat letter.