Adobe Photoshop is a raster graphics editor developed and published by Adobe Inc. for Windows and macOS. It was originally created in 1988 by Thomas and John Knoll. Since then, the software has become the industry standard not only in raster graphics editing, but in digital art as a whole. The software's name has thus become a generic trademark, leading to its usage as a verb (e.g. "to photoshop an image", "photoshopping", and "photoshop contest") although Adobe discourages such use.
Photoshop can edit and compose raster images in multiple layers and supports masks, alpha compositing and several colour models including RGB, CMYK, CIELAB, spot color, and duotone. Photoshop uses its own PSD and PSB file formats to support these features. In addition to raster graphics, Photoshop has limited abilities to edit or render text and vector graphics (especially through clipping path for the latter), as well as 3D graphics and video. Its feature set can be expanded by plug-ins; programs developed and distributed independently of Photoshop that run inside it and offer new or enhanced features.
Photoshop files have default file extension as .PSD, which stands for "Photoshop Document". A PSD file stores an image with support for most imaging options available in Photoshop. These include layers with masks, transparency, text, alpha channels and spot colours, clipping paths, and duotone settings. This is in contrast to many other file formats (e.g., .JPG or .GIF) that restrict content to provide streamlined, predictable functionality. A PSD file has a maximum height and width of 30,000 pixels, and a length limit of two gigabytes.
Photoshop files sometimes have the file extension .PSB, which stands for "Photoshop Big" (also known as "large document format"). A PSB file extends the PSD file format, increasing the maximum height and width to 300,000 pixels and the length limit to around 4 Exabytes. The dimension limit was apparently chosen arbitrarily by Adobe, not based on computer arithmetic constraints (it is not close to a power of two, as is 30,000) but for ease of software testing. PSD and PSB formats are documented.
Because of Photoshop's popularity, PSD files are widely used and supported to some extent by most competing software, including GIMP and Affinity Photo. The .PSD file format can be exported to and from Adobe's other apps, such as Adobe Illustrator, Adobe Premiere Pro, and After Effects.
If you’re a designer, marketer, visual communications employee, or work any type of creative job Adobe Photoshop skills are a must. Sometimes these apparently specialised skills come in handy at the most unexpected times. That is, those of you out there working in leadership, support, sales, development, and maybe even accounting (I admit this one is a stretch, but you never know) may someday be called on to utilise the visual prowess of Photoshop.
This is considered by some, the number one program for creating and editing visual content and being able to use it is a universally acknowledged skill worth knowing. Plus, Photoshop is fun!