Bitmap
A bitmap is a data file representing a rectangular grid of pixels. It defines a display space and color for each pixel (or “bit”) in the display space. This type of image is known as a “raster graphic.” GIF’s and JPEG’s are examples of image file types that contain bitmaps. 

Because a bitmap uses this fixed raster method, it cannot easily be rescaled without losing definition. Conversely, a vector graphic image uses geometrical shapes to represent the image, and can thus be quickly rescaled.