Stupid question. Asking anyways...

[Ætheros]

What is a vector. I know it's a certain style, but what exactly is it?

[K0LD]

Well, to make the definition as clear as possible, you work with vectors when you use basic geometric shapes to form images like lines and polyons, whereas raster art is working with dots, or pixels. I'm more akin to raster style art, but I also like working with vectors and mixing the two styles when I can.

[EvangelionUnit03]

In other words, vectors are used to make clean images that can be blown up as large as you want, though it's difficult to make a vector look nice when tracing since many of the nuances that come naturally with more conventional tools are lost.

[seiya256]

Just a bit more detail on the subject. There are basically two ways to display a 2D image, as a vector or a raster.

Rasters are what most people think of when they think of 2D graphics. When they are produced, every single dot in the image must be drawn on the screen. Uncompressed files saves all of this information as one byte per pixel per color channel. This means the file size very large as the resolution increases. The advantage is that working with raster images most closely resembles real life 2D art and is much easier to do special effects with. Another disadvantage is that the image is really only optimized to be printed at its original size.

Vectors are exactly what the name implies, mathematical representations of lines, angles, and curves. Instead of drawing a every pixel in a line, you are only marking the start and endpoints as well as the degrees of angles and curves. This allows for the information to be scaled almost infinitely with virtually no loss of quality. When first introduced, vector graphics were too computer intensive to produce anything more than logos and other fairly simple objects. Since then, both computers and the applications have gotten much more sophisticated, and people are creating very complicated graphics and in some cases near photographic images in vector format.

As a side note, traditional displays draw all images on the screen as a raster format. Traditional oscilloscopes and other testing equipment, as well as old video games like Asteroids and Tempest draws the screen in vector form.