This document discusses the concept of shirk, or polytheism, which is considered the greatest sin in Islam. It defines shirk as giving to others the rights that belong only to God, such as worship, lordship or divine attributes. Some examples given of shirk include believing other deities have power over blessings, prostrating to or making supplications to others besides God. The document warns that shirk nullifies good deeds, prohibits entry to paradise, and is unforgivable if one dies without repenting from it. Shirk is categorized based on its relation to tawheed (monotheism) and whether it is apparent or hidden.