One of the earliest bits of software that made the original Macintosh computer so interesting to use and unusual for its time was a drawing program called MacPaint.

Released in 1984 with the Mac, it is fondly remembered not only by those who used it, but also by computer scientists for numerous first-of-a-kind innovations. Those who spend a lot of time using Adobe Photoshop constantly use such features as the lasso tool for selecting non-rectangular shapes, and the paint bucket for filling closed areas with a pattern, and later, color. Both first appeared in MacPaint. The program was unique at the time for its ability to create graphics that could then be used in other applications.

MS paint wasn't based on MacPaint -it was a totally new, revolutionary product.

On a Mac I hold down the 4 (I think, from memory) key along with the usual print screen combo - it gives you cross-hairs so you can choose a section to capture, and if you then tap space the cross hairs change to a camera and you can snap individual windows.

The best bit about screen shots on Mac is that it saves them as files on the Desktop which is handy. Perhaps that's why my Mac didn't come with Paint?

On a Mac I hold down the 4 (I think, from memory) key along with the usual print screen combo

I use the OS X Grab feature for screen shots.
Handy because it'll also separate out menus or dialogue boxes, and keep the transparency of the drop shadow as well, saved as a .png (can be changed) to the desktop.
Saves cropping etc. after the event.

Yeah I use MS Paint for saving screenshots every day.

A lot of people seem to think the best way to send a screenshot is to paste the image into a .doc and email it - I don't know why, but it irritates me a little bit.