How to save a screenshot as a photo?

[Nahum]

In Paint, use "Save as" and choose PNG (Portable Network Graphics). You can also try JPEG, although Paint doesn't let you choose the image quality.

The "Bitmap" option saves an uncompressed file that won't be accepted by most websites. The only real reason to use it these days is for making image files to use as your personal desktop, or to save an image that you don't want altered by compression.