مَعْنَى الْحَجِّ وَحُكْمُهُ وَشُرُوطُهُ

What "Hajj" and "Umrah" mean, the place of Hajj among the pillars, its merits, the five conditions of the obligation (including ability), the question of the maḥram, Hajj performed for someone else, and the status of Umrah according to the schools.