Archives take a file(s) and compress them into a new file, that can be extracted to form the original contents. Why do this? Well, if you have a bunch of files that you want to backup or transmit over the internet, this is usually the way to go - since it compresses, it makes the transmission faster, and also, it makes files easier to manage. OS X Tiger has a built in program that ZIPs the files for you. ZIP is just a type of archive format -- there are plenty of formats out there. Mac users may be used to seeing '.sit' files, made popular by 'Stuffit' a program that has been used on Macs for many years, and still is today. You won't get much [if any] compression from files such as jpeg pictures - they are already compressed. However, a Microsoft Word document isn't. Regardless, let's say you have 20 files to send to someone -- they would much rather receive 1 attachment, than 20. Here is how to do it: First, from the 'Finder', select a file(s) that you want to archive. Next, hold down 'Control' and 'Click' on them. When the contextual menu appears, choose 'Create Archive'. This may say the number of files, if you have chosen multiples, but if it is just one, it will put in the name of the file - such as 'Create archive of emailbackup'. Next, in the directory where you do this, a new file will be created, 'Archive.zip'. You probably want to rename it to something more descriptive. Be sure to keep the '.zip' extension though, since that is how the Mac knows what kind of file this is. To extract the contents, simply 'double click' the mouse on the archive file. If you are sending to a 'Windows' user, they may need a third party app to extract the files, such as 'WinZip'... but every MS Windows machine I have ever seen has had this app already installed.