I found this great video on YouTube with the master himself, Matt Cutts explaining ALT tags. ALT tags are important because they tell the person reading what the image (photo) is about.
It is easy to do on Activerain, after you upload your photo, just add a title tag and image description. The title tag will be what shows up when someone holds their cursor over the photo. Google likes us to use ALT tags, enough said.
Here is an example: Put your cursor over the image and hold it there. See it?Now enjoy the show.