Photoshop is a raster graphics editing software developed by Thomas and John Knoll in 1987 and published by Adobe. It allows editing and compositing of raster images in multiple layers and supports masks, alpha compositing, and color models like RGB, CMYK, and grayscale. The presentation discusses using Photoshop for various purposes like social media posts, web banners, UI design, restoration, retouching, magazine covers, typography, movie posters, digital painting, photography, matte painting, GIFs, effects, and image manipulation. Examples are provided of before and after edits for restoration, retouching, digital painting, and photography.