Linux has a very rich and powerful filesystem called procfs—proc for process. It is usually mounted under /proc, and it contains pseudo-files and directories that contain valuable runtime-generated information on processes and internals information. In a nutshell, procfs serves as a UI for two key purposes:

• It serves as a viewport into detailed process, thread, OS, and hardware information.
• It serves as the place to query and set kernel-level tunables (switches and values for the core kernel, scheduling, memory, and network parameters).

Taking the trouble to study and use the Linux proc filesystem is well worth it. Pretty much all the user space monitoring and analysis tools are ultimately based on procfs. Find further information in the links provided in Further reading section on the GitHub repository.