* JPEG (Joint Photographics Experts Group) – pronounced ‘jaypeg’ and you will sometimes see it shortened to just JPG. This format is ‘lossy’ in that the more you compress the image and thus reduce file size, the greater you will lose clarity and detail. JPEG graphics can render in full colour and are ideally suited to the display of photographs.
* GIF (Graphics Interchange Format) is ‘lossless’ in that the compression process does not involve sacrificing quality. GIF graphics are limited to 256 colours, which is fine for computer graphics with hard edges and block colours, but not so good for photos. They can also have a transparent background, which can be useful if you want to display your images in anything other than a simple rectangular arrangement.
* PNG (Portable Network Graphics) – pronounced ‘ping’ – is another ‘lossless’ format but is not restricted in colour rendition, making it a superior format to GIF. PNGs are ideal for computer-generated graphics such as buttons, logos, diagrams and maps, but are less suited to photographs, where the resulting file size is likely to be excessive. Be a little careful, because not all online applications – or corporate forewalls – support PNG.