Password Protect Zip Files in Mac OS X

If you’re familiar with the command line, the syntax of the encrypted zip command is as follows:
zip -er [archive] [file]

The -e option means encrypt the archive; the -r option tells the command to travel the directory structure recursively.  These encrypted zip files will maintain password protection across platforms, meaning you can send a protected zip file to a Windows user and they will still need to enter the password in order to view the contents.