Image Formats

There are many formats available for storing images. However, many browsers are unable to display more than one or two formats "inline". The two most common formats in use (and supported by browsers) are GIF and JPEG, with GIF being the more popular of these two. Following is a list of formats along with a small image in each format. You can use it to see which formats are supported by your browser.

Remember that a separate network connection has to be made for each image in your document. So although small images may be transferred quickly, putting many of them in a document can make it take extra time to transfer due to the overhead involved in opening extra connections for each image. Using the same image repeatedly (such as colored bullets) does not incur the same cost since browsers usually cache the image, and will only need to transfer it once even if it used more than once in the document.

GIF87, non-transparent background. 7kb	GIF89, transparent background. 7kb	GIF89, interlaced, transparent background. 7.1kb
JPEG, high quality. 12kb	JPEG, medium quality. 5.5kb	JPEG, low quality. 3.1kb