Using the wrong file format for images is one of the most common graphics mistakes made on the Web. TIF, GIF, PNG or JPEG? Some are better than others depending on the usage. So here is an overview of the most popular file formats and their best uses.

GIF (Graphic Interchange Format) can only contain up to 256 colors, so this file format is most commonly used for images with fewer and flatter colors, such as line art, charts, graphs, or text set as graphics. (They are not ideal for photographic images.) One hallmark of GIFs is that they maintain resolution and sharpness even when compressed.

JPEG (Joint Photographic Expert Group , sometimes also referred to as JPG) allows for up to 16 million colors and therefore is best for images with many colors, such as digital photographs or scanned artwork. Most images found on the Web and sent via e-mail are JPEGs. This file format is the smallest and should be used when file size is all important.

TIF (Tagged Image File) One of the more commonly used graphics files of the "pre-Windows" days but no longer used much on the Web. TIF is the undisputed leader when best quality is required so it is commonly used in commercial printing or professional environments. Plus, TIF files can be easily converted to GIFs.

PNG (Portable Network Graphics) A more recent file format for the Web, PNG files are compact and versatile and can combine the best features of GIF and JPG. Like GIF files, a PNG file compresses the graphic without losing any data. On the downside, visitors with older browsers will not be able to see PNG files.

So, to put it simply:

If a graphic has only a few colors (like a chart or line art), choose GIF. If it has a lot of colors (like a photo), choose JPEG.