Photostream is an excellent part of iPhoto and your iOS devices. It allows you to quickly sync files between the two devices quickly and easily. The problem with this is that it downloads all of the files on to your Mac. These can then take up more and more space as time goes on. This post will show you where these files are stored and how to remove them. Its a quick video that is very useful if you are low on disk space.
You can watch the video below or on Youtube.