Every package in Latex comes with its documentation. Hence, most of the Latex-distributions contain the “complete” documentation by default, which is accessible without an internet connection.

In order to access a documentation file of a certain package, go to the command line and type:

texdoc package-name

E.g.

texdoc subfigure

The software used to display the package documentation depends on your operating system. Under Windows it might be Yap, under Mac OS X TexShop if you have it installed.