Shirk is an Arabic term that refers to the act of associating partners with Allah in worship. It is considered one of the gravest sins in Islam, as it undermines the concept of monotheism, which is central to the faith. Shirk can manifest in various forms, such as idol worship or attributing divine qualities to other beings. There are two main types of shirk: major and minor. Major shirk involves outright denial of Allah's uniqueness, while minor shirk includes actions that may lead to major shirk, such as excessive reliance on intermediaries in prayer. Both forms are discouraged in Islamic teachings.