FAQ is an abbreviation for Frequently Asked Questions. It is a list of often asked questions by customers and responses on them.
FAQ in practice: A list of frequently asked questions and answers began to be used on websites and discussion forums where users have been asking the same questions. So as to not necessarily answer them again and again, it began to use the FAQ list. They have become a common part of feedback and presentation of the key features of the software, website or user manuals for anything. They are also used as a help where the user focuses on questions while can read the response.