With so many file formats to choose from, it can be a little confusing working out the difference between them. Here's a breakdown of the most commonly used picture file formats to help decide the best way to save your photos or images:
JPG, jpeg or Joint Photographic Experts Group is the most common format for photos and high quality images. The letters at the end of your file will help you determine that your image is a JPG as it will appear as imagename.jpg. Most modern digital cameras will automatically transfer photos to your computer in JPG format.
GIF stands for Graphics Interchange Format and is best used for saving graphics - flat shapes with solid blocks of colour. Because of the way a GIF file is contstructed, simple graphics get saved in maximum quality with minimum file size. GIFs have a limited colour range, but they support animation - so you can make moving pictures.
PNG stands for Portable Networks Graphics. Unofficially, they're called "PNGs, Not GIFs". Think of a PNG as a grown-up GIF - they accomodate a wider range of colours and save graphics with a smaller file size, but don't support animation. PNG images are widely supported, but aren't as common as JPGs and GIFs, which have been around for longer.