What the heck are raster and vector graphics and why are they different?

Computer graphics are produced in two ways. Raster graphics are created with pixels and are referred to as bitmap images. Raster files are best for photography and continuous tone images. When a raster graphic is scaled up on a computer screen the pixels can be seen as squares each with their own color and value (dark to light).  They cannot be scaled up in size without losing image quality. In a public relations campaign photographs may be sent out to print publications. It is best to know the magazines’ technical print information. An image will print blurry in the magazine if the photo is sent out with a dpi that is too low.

Vectors, on the other hand, are resolution independent. They are created with paths (points, lines, and bezier curves) which are based in mathematical equations. Use of vector graphics is much more flexible. They can be scaled up and down without losing their crispness. Line art (illustrations), type, and page layout programs all use the vector format. Logos are best when created in the vector format because the art will always be clean and not bitmapped. Vector graphics are used in both print and web design.