GIF

Graphics Interchange Format. A low-resolution format used for Web graphics and other low-resolution images. It uses 256 colours instead of millions of colours so the file size drastically reduces. The GIF format is a great format for simple images with large areas that are all the same colour as their colour palette is limited by their only having 256 colours. GIFs are best used for logos, cartoons and line-drawing images.

It is a lossless format that does not degrade in quality. GIF file formats are also used in animation.

JPEG

Joint Photographic Experts Group. Also referred to as JPG. The JPEG is a compressed photograph file format that has become the most commonly found picture file type on the Internet. This is mainly because JPEGs offer a large amount of flexibility in terms of compression and picture quality. JPEG Compression acts upon the theory that if two areas are almost exactly the same colour, we are going to see them as the same colour. The entire area can be saved as one colour, making a lot less data to be stored in the file, and the compressed version becomes even smaller. The smaller the image, the less storage space and the quicker to upload and email when sharing.

JPEGs can maintain a reasonable image quality while making the file size of the image much smaller. It is possible to significantly reduce the storage and file sharing size of a JPEG file by reducing the image quality. In most cases, you can't tell the difference between the original and the compressed JPEG.

As JPEG is a lossy format, each time a picture is edited and re-saved in the JPEG format, it loses a degree of quality. Do not save as a JPEG several times, because each save will degrade it further. Like a photocopy of a photocopy, the quality of the picture will suffer every time you copy the copy. For this reason, when you're editing your photos, always start with a lossless format (like PNG or TIFF) or the software’s own standard, and don't convert your image to the JPEG file format until the editing is done and you are ready to file or share it. If you're going to email pictures or post them to the Web, this is the format to use.

PNG

Portable Network Graphics are a newer, more powerful GIF. It has many of the features that make GIF useful on the Web, without the 256 colour limitation. They support truecolour, a 16-million colour palette. PNGs are lossless, so you do not lose quality when you convert to PNG, making them great for editing photos. Most web browsers support PNGs, but they can still be quite large. In many cases, the best choice is to edit a file in PNG format, then convert to JPEG for file sharing.

RAW

The internal format of a digital camera. Many cameras "pre-process" images. They will do JPG compression, white balancing, and a number of other adjustments. The RAW image is the starting point for all of these.

Digital photographers may prefer to shoot in RAW format  so that they can make their own changes to these items and have more control over the finished look. Raw format does not get any processing in the camera, allowing them to adjust things like white balance and exposure after the picture has been taken.

The main disadvantage of RAW is that every brand is different and not all formats can be read by photo editing software. So before you use your camera RAW setting, make sure you have the software that can handle it.

TIFF

Tagged image file format files are a lossless bitmap graphics format that is versatile and very high quality and is used for saving and printing high-resolution images. Tiffs support up to 48-bit colour depth. However, they have a wide variance and an image viewer that can view one type of TIFF may not be able to view another and Tiffs are not widely supported by web browsers. This plus their large file size makes them impractical for online photo sharing. Tiff file format is not a common format. Quite often the standard format of JPEG is used.

Vector images

Graphics that are perfect for drawing logos and similar graphics as they are based on mathematical calculations rather than pixels or dots. This means that they are not dependent on resolution and can be scaled to size without losing sharpness or image quality. Vector images are a favoured image format for a lot of graphic designers.

Encapsulated Post Script (EPS) files are usually created in illustration programs. They provide the best (vector) format when printing high resolution illustrations.