What is the meaning of bai'at? Is it compulsory?

Answer

Wa alaikumus salaam

Bai'at is not compulsory but the purpose for which bai'at is done is compulsory and that is islaah. Islaah means to inculcate good characters and to purify one's nafs from evil characters.

Practically it is impossible to do it without the help of a shaikh kaamil or a spiritual guide. Thus, it is practically important to do it under the monitoring of a spiritual guide. To submit oneself for this purpose to a shaikh kaamil is called bai'at. A sheikh kaamil is somebody who is well known for his competence and efficiency in deeni matters by the majority of reliable Ulama.