You can create .rar files just like a zip file by putting a bunch of pics in it. The other way .rar files are used is to break a movie into smaller downloadable segments.
For example, you have a 100 MB movie and it would take too long for you to upload and anyone to download. Winrar can be used to split that 100MB Movie into 10MB segments. Easier to post and download. For the downloader, he/she would need to download each and every segment of the split file. Once all the segments have been downloaded, you use winrar to rejoin the segments to get the 100MB movie clip.
Note: You can not to just download one segment and use winrar to unlock that segment. Won't work.
More about the program....
http://www.win-rar.com/