This one page contains only some very basic information and hints for the newbie. Its about monitor or screen resolution, scanning, web images, file types, color, etc. It is not a tutorial.
Vector is a drawing file using lines and arcs and relatively small in size.
CDR Corel Draw. For distribution over the Internet and other online services. The file, particularly a photo, can be very large in size depending on the resolution. GIF Compressed file for non-photo Internet graphics. JPG Compressed file for internet photos.