This is what most users switch to zsh for: completion. In this chapter, we'll meet one of the best features of zsh: compsys. Known as "the new" completion mechanism, this chapter focuses on its various functions and configuration. We will learn to tweak the completion behavior so that it's no longer restricted to filenames and bump it up using styles and our own functions. When we're done, you should be able to read most zsh scripts as well as tweak many of the existing functions.