The PSD files created by Adobe Photoshop are known as bitmap or raster images. Essentially, they're essentially made up of a grid of colored pixels.
The answer is that Photoshop is a bitmap editor, which means it edits images in a grid of pixels. However, Photoshop also has some vector features, which means it can create and edit vector graphics as well. If a user needs to work with bitmap images, then Photoshop can be used as a bitmap program.