Short for Photoshop document, PSD is the default file format of documents created in Adobe Photoshop. The PSD format allows a Photoshop user to save all the information needed to continue editing the file later, such as layers, guides, and transparency masks. Files saved in this format have the file extension .psd.
How to open a PSD file
Not everyone has access to Adobe Photoshop. However, other programs allow you to open a PSD file. Below is a listing of applications which can view, and in some cases, edit, as well as save files in the PSD format.