When sending large files, compressing them makes them smaller. You can also compress an entire folder of files, including sub-folders into one Zip file. Zip utilities are very easy to use, and there are many good ones available for free.
Advantages of zipping files include:
- Your files will upload and download faster
- You can send files and folders as one file "package", instead of sending many files individually
- You'll use less bandwidth and save money
Here is some information from Microsoft on using ZIP files with windows. Mac OS also has built-in support for working with Zip files.
http://office.microsoft.com/en-us/help/HA011276901033.aspx
The .ZIP file format is a well established standard so it does not matter which utility you use. You'll need a ZIP utility to compress or uncompress files. Windows and Mac have built in zip / unzip software. You can use that, or you can use a utility from a third party software developer such as TyphoonZip.
TyphoonTools provides a free utility for compressing files and folders into .zip or .rar file formats. You can download it using the link below:
http://www.typhoonzip.com/typhoonzip.php
TyphoonZip works with many versions of Windows.
Some screen shots of the TyphoonZip utility are below.