Other Formats
Raw
This is not actually a format, but refers to how images can be stored prior to being saved as a JPG, GIF, etc.
BMP
This is MicroSoft's Window Bitmap format. BMP files are quite large and often do not offer any benefit over using PNG or TIFF. If you need a Windows icon, you can use this format. Otherwise, select a different format.
PSD
If you have ever used Adobe PhotoShop, you would have seen this image file type. It saves layers and other information.
ICO
This format can be useful for Windows icons too like the BMP, but where you might see this file type used more often is when you create a favicon for your website. A favicon is also referred to site icon in WordPress.
PDF & PostScript
These are vector graphic formats, not raster (pixel) graphics, like the other image file types discussed in this WA tutorial. A vector image is a collection of drawing instructions involving points, lines and curves, such as what you will see in text in a PDF format.
SVG
This file format stands for Scalable Vector Graphics but you will not see this format as often.