Who are "Ahl al-Hall wal-'Aqd" (the people of loosening and binding), and what are the conditions that must be met in them for the selection of the Caliph?

What Ibn Hazm and other scholars mentioned, and what the majority of Ahl al-Sunnah adopted, is that the Imams must be from Quraysh, because this has been mentioned in authentic Marfu‘ (traced back to the Prophet) hadiths. As for the people of authority and decision (Ahl al-Hall wal-‘Aqd), they are the influential figures among rulers, scholars, leaders, politicians, and prominent members of society. The conditions required for them are justice, knowledge, sound judgment, and wisdom.