Ahl-ul-Bayt means literally household, and refers to the household of the Messenger of Allah (Peace be upon him)

Ahl-ul-Bayt أَهل البيت in Arabic language means literally household, and refers to the household of the Messenger of Allah (Peace be upon him). They are quoted -and honored- in the Quran. But there's a difference between Muslim sects about whom exactly are among ahl-ul-Bayt.