What is the status of Hajj in Islam? And upon whom is it obligatory?

Hajj is one of the pillars of Islam, an obligation established by the Book of Allah, the Sunnah (definition) of His Prophet, and the consensus of Muslims. Whoever denies its obligation disbelieves, and whoever abandons it out of negligence is in grave danger. A Muslim must hasten to perform Hajj once the conditions for its obligation are met, which are: Islam, بلوغ (adulthood), sanity, freedom (a condition about which some scholars differed), and ability (in terms of financial means and physical health, and for women, the presence of a محرم (unmarriageable kin)).