Windows XP, Windows Vista, Mac OS X, and later versions of these operating systems can create ZIP files without using third-party applications. Below are reproductions of a Microsoft knowledgebase article and a Mac Pro Tip of the Week that describe how to use the built in zip support.
If you do not use XP, Vista or OS X you will need to purchase a commercial package or download and use an open source application. A list of commercial and open source packages is at the bottom of this page.
How to create and use compressed (zipped) folders in Windows XP
If you want to create a compressed folder within another folder, go to method 1. If you want to create a compressed folder on your desktop, go to method 2.
Method 1: Use My Computer to create the compressed folder
Follow these steps to use My Computer to create a compressed folder:
On your desktop, double-click My Computer, and then open the folder in which you want to create the compressed folder. For example, if you want to make a compressed folder in the root folder of drive C, double-click My Computer, and then double-click drive C to open the root folder.
Note: If you do not see a My Computer icon on your desktop, click Start, and then click My Computer.
On the File menu, point to New, and then click Compressed (zipped) Folder.
Type a name for the new compressed folder, and then press ENTER. Your new compressed folder is displayed as a folder icon with a zipper. Depending on which folder options that you have set, a .zip file name extension may also appear.
Method 2: Create the compressed folder on the desktop or in a folder
Right-click a blank area on the desktop or in an open folder, point to New, and then click Compressed (zipped) Folder.
Type a name for the new compressed folder, and then press ENTER. Your new compressed folder is displayed as a folder icon with a zipper. Depending on your preferences, a .zip file name extension may also appear.
How to move files and folders to and from a compressed folder
You move files and folders to or from compressed folders exactly as you move them to or from uncompressed folders. For example, you can drag files or folders to the compressed folder. When you move a file or a folder to a compressed folder, that file is automatically compressed. A file that is moved from a compressed folder is automatically uncompressed.
Mac Pro Tip of the Week: Making ZIP Files (Compressed Files) in One Click
One of my favorite Mac OS X features is the ability to create ZIP compressed files from within the OS (basically, this shrinks the file size, ideal for files you’re going to email — smaller file sizes mean faster file transfers).
To create a compressed file, either Control-click on the file and choose Create Archive (which is Apple-speak for “make a compressed ZIP file”). or you can click on a file, then go to the Action menu (the button that looks like a gear up in the Finder window’s toolbar), and choose Create Archive from there. Either way, it quickly creates a new file, with the file extension “.zip.” This is the compressed file.
You can also compress several different files (like three, for example) into one single archive file - just Command-click (or Shift-click contiguous files) on all the files you want included, then choose Create Archive of X Items from the Action menu. A file will be created named “Archive.zip” (that’s it!).
Commercial and Open Source Zip Utilities
"7-Zip is open source software… You can use 7-Zip on any computer, including a computer in a commercial organization. You don't need to register or pay for 7-Zip. But you can make a donation to support further development of 7-Zip."
"PKZIP is the industry-leading security and compression utility that zips and unzips files, greatly reducing transmission times and required storage space. PKZIP allows you to exchange data with a wide variety of systems including mainframe, midrange, server and desktop systems."
"WinZip® is the most trusted way to work with compressed files. No other compression utility is as easy-to-use or offers the comprehensive and productivity-enhancing approach that has made WinZip the gold standard for file-compression tools."
StuffIt Deluxe® http://my.smithmicro.com/mac/stuffit.html
"StuffIt Deluxe provides advanced compression of your MP3s, PDFs and graphic files. StuffIt’s newly patented technology compresses 24-bit images, including TIFFs, PNGs, BMPs and GIFs. Only StuffIt offers optimized compression of Apple iWorks and Microsoft’s Office documents. Say goodbye to cross-platform hassles thanks to StuffIt’s ability to create and open 100% Windows compatible Zip archives. Search and access virtually any compressed data with StuffIt’s support of over twenty compression formats. Set automatic backups of your acrchived data to CD/DVDs, FTP and .Mac. Secure your archives with password protection and strong 512-bit encryption."