There are a number of ways to capture and share what you see on your computer screen. One that I have used for a very long time is SnagIt (I'll write a post about that later). The disadvantage (and advantage) of SnagIt is that you get a graphic that you can then edit and then share with others in a variety of ways. But what if you were in an IM conversation and wanted to quickly and easily share something. You should take a look at Gyazo. I liked it so much that I went "ninja" (i.e. became a paid member). Gyazo will let you quickly take a screenshot and then show you a secret web address for it which you can send quickly to someone else in an email, an IM, etc. Quick and easy is the point. NOW it even lets you do GIFs.
To illustrate what Gyazo can do, I activated Scrivener (another piece of software that I will do a post on later) and the screen shot that I made can be seen at the link below.
Pretty cool uh? I haven't tried a GIF yet, but it is on my "to do" list.