What kind of software lets you take a picture of the computer screen?

I have Windows XP and to take a picture of the screen takes no particular software other then to simply press the print screen button on the keyboard (top row third from the right) You can then go into Word and simply paste the picture onto the page. If you only want a part of the picture on the screen open paint paste the picture on the paint screen and in paint you can select the part of the picture you want to keep ofter you have the picture you want in paint just save it as a jpg tiff or whatever you prefer into my pictures or your preferred album. you can even take pictures of movies on the screen that way if your timing is good without having to get any particular software that is not on the average computer anyway.