Imam Al-Mahdi (AS) is the twelfth and last Imam in Islam. The Prophet Muhammad (SAWA) has clearly said that (My successors will be twelve, all of them will be from Quraysh) Saheeh Al-Bukhari; Hadeeth number 6682 and Saheeh Muslim; Hadeeth number 3393 and 3394 and 3395 and 3396 and 3397.
Imam Al-Mahdi (AS) was born in Samarra in Iraq on 15 Sha'ban 255 After Hijra when the tyrant government of Abbasid were after trying to kill him knowing from hundreds of Hadeeths that he will be the Imam who will establish the Justice on this earth and remove all the tyrants.
Imam Al- Mahdi (AS) is living in this earth but Allah (SWT) has protect him from the evil of tyrants by making public unable to see him. Only few very sincere believers could see him but no one is allowed to publicize his place.
Imam Al-Mahdi (AS) guides people and protects them in the suitable way which Allah (SWT) guides him.
He will return to the public life when Allah (SWT) permits him, and will then establish the world of peace and justice.
Sincere believers are always ready to serve Islam under his leadership and guidance and always prepare themselves and their families and societies for that.