What file format is commonly used for Photoshop project files?

The commonly used file format for Photoshop project files is PSD, which stands for Photoshop Document. This format is specifically designed for use with Adobe Photoshop and allows users to save all the layers, effects, and adjustments within a project, making it ideal for ongoing design work.

When using PSD files, designers can easily return to a project for future edits while maintaining the quality and flexibility to manipulate layers independently. This is particularly critical in graphic design as it allows for non-destructive editing, meaning changes can be made without permanently altering original image data.

In contrast, other formats serve different purposes. JPG is a compressed image format that is widely used for photographs but does not support layers or edits, making it less suitable for projects that require ongoing adjustments. PAT is a format used for Photoshop patterns, while PDF is typically utilized for document sharing and printing, preserving formatting and layout but not enabling the same level of editability as a PSD file. Therefore, for working within Photoshop itself, the PSD format is the most appropriate choice.