pstree displays all running processes in a tree like diagram on a terminal or console. The tree is rooted at either pid or init if pid is omitted. If a user name is specified, all process trees rooted at processes owned by that user are shown.
pstree is an easy way to find parent processes, but the majority of the time just using ps will do the job to find a specific process.
pstree visually merges identical branches by putting them in square brackets and prefixing them with the repetition count, e.g.
init-+-getty |-getty |-getty `-getty
For options, see its man page
This document was actually taken from the actual man page found on most systems which was written by Werner Almesberger and Craig Small on September 26, 2003.