Computers use two kinds of art: bitmap art, and vector art. Files using bitmap art usually have file name extensions such as .GIF, .BMP, .JPEG, .JPG, and .PCX. Vector art files have a file name extension of .EPS.
Bitmap art and vector art have different methods of storing or saving an image. Bitmap makes use of pixels, with each corresponding to a color. These dots are arranged in a particular order (which are saved as a series of numbers) to create a shape or form which the eye sees as a picture. In a way, it works like a very complex pointillism painting. Vector art, on the other hand, saves the image not as points but as lines, storing the coordinates of where the line starts and ends. Vector art actually simulates the way that the brain sees and stores images (or at least, how research shows the brain to work).
Vector art, however, can only make very simple images, such as lines, curves and shapes. Composed images tend to have a very simple, cartoonish feel. It is not capable of rendering realistic images, or of rendering the soft effects and complex color variations found in bitmap files. However, it is ideal for making signs and logos—which, in fact, are more memorable and effective if they are kept stark and simple.
One advantage that vector art has is that it has very small file sizes. Even images that are as large as a poster will only take a few kilobytes of computer memory. Bitmap art, on the other hand, can require over 1 megabyte for one large, high-resolution photo. Vector art is also easy to enlarge with minimum risk of distortion.