Salesforce is a company that uses the cloud. Usually, businesses use this company for their business needs. In all technological devices, problems and glitches are going to occur. When you want to fix those problems or defects, you will need to debug them. Some computer and computer systems like Salesforce implement a debugging statement in order for those problems to be resolved prior to them causing problems to the user.
These statements pinpoint the exact problem going on in the system. In Salesforce, there are a few different levels of debugging statements that were generated by the user. Within all of these levels, a user debug is in all of them. However, the minimum log level to see the user generated debugging statement is called WARN.