First, you pick a folder to test to. This folder can be on a local drive or USB drive, etc. to test the drive speed, or a shared folder on your network to test your network speed. Next, LAN Speed Test builds a file in memory, then transfers it both ways (without effects of Windows/Mac file caching) while keeping track of the time, and then does the calculations for you. For more advanced users, you can test to LAN Speed Test Server instead of a shared folder to take the slower hard drives out of the process as you are testing from one computer's RAM to another computer's RAM. Simple concept and easy to use. You'll find that LAN Speed Test will quickly become one of your favorite network tools!