A long-time Small Dog customer asked me about an item that fleetingly appeared in his dock. It was a generic-looking green icon with a zipper on it called Archive Utility, and when he used Spotlight to search for it, it was nowhere to be found.
Many of the items you download and receive in your email are compressed files. File compression is nothing new and is exactly what you think it is: when you compress a file, you make it smaller. This reduces bandwidth loads and expenses on the server side, and can help you save disk space on your computer. However, compressed files cannot be directly accessed; they must first be decompressed.
Back in the days of 20-megabyte hard drives (my LC II had a 20MB drive in the early ’90s), file compression seemed more relevant for conservation of hard disk space. These days, it’s more often used to shrink email attachments and other downloads. Mac OS X has always included a built-in compressor and decompressor. By right-clicking on any file or folder in the Finder and selecting “Compress” from the contextual (pop-down) menu, your Mac will create an archive in zip format.
When you open a compressed file, Mac OS X launches an application called Archive Utility. Its sole purpose is to compress and decompress files. It’s located in /System/Library/CoreServices, and Spotlight doesn’t search there. If you poke around the /System/Library and /Library areas of your hard drive, there’s plenty to learn if you Google intelligently and use extreme caution when moving or deleting anything. Actually—don’t move or delete anything. Just explore and learn!