Photoshop is capable of saving and opening about a billion file formats, and with the introduction of 3D capabilities back in Photoshop CS3 (Extended edition), that number has grown substantially. Add to that the ability to extend Photoshop's capabilities by installing third-party file format plug-ins, and ...well, you see where this is going. Some of the available formats are obscure or even defunct, but it's nice to know that Photoshop can most likely handle just about any image format you attempt to open with it.
Each file format has a purpose, and in most cases, offers some form of compression so that the file takes up less hard disk space. Let's take a look at some of the file formats available for you to choose from.
As mentioned earlier, PSD is Photoshop's default file format. It's specifically optimized for Photoshop's features and capabilities. Document attributes, such as layers, layer styles, alpha channels, spot color channels, and Smart Objects are all preserved in the PSD file format. Additionally, the close integration between Adobe's Creative Suite applications means that programs such as After Effects, Illustrator, Premiere, and Go Live can open — and in some cases, export — PSD files and preserve most of their attributes. You can also open PSD files in earlier versions of Photoshop, but features that aren't supported in those earlier versions can be lost.
To be on the safe side, if you know you'll be sharing ...