Files can be put in special compressed archive files, thus saving memory. Multiple files can be put in a single archive file, which can be useful on the web when sites like Wetpaint set a limit one the number of files you can have.

Files ending in ".zip" are a type of compressed archive files typically found on Windows compatible computers. If you find a zip file that you want to open, right-click it and look for an option like "unzip" or "extract compressed files". If you want to compress files, highlight the files you want to add into the same compressed archive, and right-click the group; you should find an option like "zip," "add to a compressed archive," or "send to > compressed archive."

To learn more about zipping or unzipping files, see the Microsoft page about it, or search for "zip files" on a search engine such as Google.