Pixel-based images, also referred to as Raster graphics or Bitmaps a made up of small squares or dots known as pixels. A pixel (pixel-element) is the smallest editable element in a pixel-based image. A pixel-based image may be stored as a number of file formats such as a jpeg, png, gif, tiff or psd. Unlike Vector based imagery, pixel-based imagery is resolution dependent and can not be scaled up without loosing quality. Resolution is typically measured by the number of pixels per inch (ppi). The higher the number of pixels per inch the higher the image quality will be and the larger the file size will become. Each pixel in an image has a position on the document and an RGB value. By altering the RGB values and positions of various pixels in an image using a pixel editing program such as Adobe Photoshop, we can retouch and alter an image in a vast variety of ways. All digital photographs are pixel-based as are the majority of of images within a web page.
This video takes an imaginary journey into the land of the pixel: