Logging is the process of recording the activities of a program. Logs can be a textual flow in a specified format, which prints to a console or writes to a file. Rust has a great logging ecosystem based on the log crate. It is worth noting that the log crate contains macros without a real logger implementation. This gives you an opportunity to use different loggers depending on what you need them for. In this section, we will start to use the log crate in our microservices to learn how logging levels work and how to set the desired level of logs you want to see.