texdoc is a tool that helps you find and view documentation in texlive. Its primary function is to locate relevant documentation for a given keyword (typically, a LaTeX package name) on your hard disk, and open it in an appropriate viewer. For instance, say that you want to view the documentation for the package biblatex, then you issue the following in a terminal
texdoc biblatex
If you use auctex you can access texdoc via C-c ? (or M-x TeX-doc).
