PNGs have an alpha channel, so you can have irregularly shaped images for things like icons.
JPG is a lossy format. This is good for webpages to use, because smaller, compressed files save load times. However, the downside to this is that the compression cannot be disabled. Every time you save an image in JPG, it losses data. Save, edit, save and edit again for a few times, and you’ll find yourself with an image of disgusting quality.
PNG on the other hand is a lossless format. Don’t be fooled to think that your image will lose quality when you choose to compress a PNG when you export from Photoshop – it’s actually lossless compression. Although PNG compression isn’t as aggressive as that of JPG in terms of file size, it’s still a win-win situation. You get a compressed file size and uncompromised quality.
Other image formats such as TIFF have very similar features to PNG, but they are not as widely compatible.For example, TIFF is not supported on the stock Photos app on Android. Contrarily, PNG is supported on virtually any system that can display images, from TVs to smartphones.