Ok, so here we are. You've come here because you've never seen the word raster, much less have any idea what it means. I'm here because I've seen you use the word vector incorrectly. And it bothers me. So here we go: Raster Raster images are the most common. And by most common, I mean 99% of anything you see on the net will be raster. Raster images have extensions such as: .jpg, .gif, .png, .bmp, .tif, etc. Raster images are defined by pixels. They are simply a grid that tells the computer this pixel at this coordinate is this color. Anything you export out of Photoshop will be a raster image. Yes, even those "vector" pictures everyone posts are raster. I'm sure at this point you must be thinking, "But Kyoji, if a "vector" picture is raster, then whats vector?!" And so I tell you. Vector Vector images are the least common. And by least common, I mean 1% of anything you see on the net will be vector. Vector images have extensions such as: .eps, .ai, .swf, etc. Vector images are defined by a mathematical formula. They are simply a shape that is defined by an equation on a coordinate plane. Anything you export out of Illustrator or Flash (with a few exceptions) will be vector. Since a vector image is defined by a formula, the image can be enlarged or shrunk to ad infinitum and never lose quality. Next time you watch a Flash movie on Newgrounds (because I know you watch movies on Newgrounds) right click on it and select "Zoom in". You'll notice the curves and edges of objects never get jaggy. Cool, yea? It's important to note that even if an image was made in Illustrator for example, if you are looking at it through a webbrowser, 99.999999% of the time it will be raster. So don't call it vector. Or I'll yell at you. Now for my bone of contention. Since you now know the difference, please, PLEASE do not comment on a raster image and say "I like your vector " or "Your vector is so cool!" Vector is NOT a style, nor adjective. For the love of design, do not use it as such.