.SITES File Extension
File TypeiWeb Site Design Project
What is a SITES file?
File created by iWeb, a Web developer program for beginners; knowledge of HTML is not required; contains pre-designed Web page layouts, text, and graphics; can be published to a live website when complete; similar to .SITES2 files.
SITES files are used for storing websites as they are developed. iWeb saves them to the /[user]/Library/Application Support/iWeb directory without prompting the user for a save location.
NOTE: iWeb is part of Apple's iLife application suite.