What would I be using the "Snappy" program for if I got this job?

Snappy was mentioned in this job description. I finally figured out that it’s a screen shot program, and I downloaded a free version on to my computer. when I started to play around it hung up my computer, so I killed it.
What would I use this for in my job, and why don’t they just take screen prints instead of using this program? What’s special about it?