The FAA does not necessarily endorse any of the software vendors listed below.
Windows has the capability of opening zip files without requiring the installation of additional software. After downloading, open the zip file and a window will appear showing the contents of the zip file. Drag and drop to extract the contents, or open the files normally.
7-Zip is a free program available to users of Windows. 7-Zip can extract a wider range of zip file formats than Windows' native functionality.
Mac OS X
In OS X, zip file functionality is built into the Finder.
StuffIt Expander is a free program available to users of Mac OS X.