None of these formats are compressed, so their file sizes are quite large compared to JPEG images. When working on images in Photoshop, there are many features, such as layers, that serve a purpose only when editing. For this reason, Photoshop has its own native format you use to save file while working on them. This format saves everything you've done to the image so you can just reopen the file and continue working. It has since become a Macintosh standard.
Many digital photos end up on the Web or attached to e-mail so they are viewed on the screen.
For these purposes, small files that are easy to send over the Internet are favored. The leading format for images used in these ways is JPEG, the format most often used to store captured images. However, rival formats have been developed to improve on JPEGs or to serve other purposes. Here are some of them. PNG, like GIF is a lossless format, but it has some features that the GIF format doesn't.