The construction of images for the web is a little outside of the remit of this website, but it is worth noting a few things…

The most commonly used file formats used for images are JPEGs, GIFs, and PNGs. They are compressed formats, and have very different uses.

A JPEG (pronounced “jay-peg”) uses a mathematical algorithm to compress the image and will distort the original slightly. The lower the compression, the higher the file size, but the clearer the image.

JPEGs are typically used for images such as photographs.

A GIF (pronounced “jif”) can have no more than 256 colors, but they maintain the colors of the original image. The lower the number of colors you have in the image, the lower the file size will be. GIFs also allow any pixel in the image to be transparent.

GIFs are typically used for images with solid colors, such as icons or logos.

A PNG (pronounced “ping”) replicates colors, much like a GIF, but allows 16 million colors as well as alpha transparency (that is, an area could be 50% transparent).

PNGs are typically used for versatile images in more complex designs BUT they are not fully supported by some older browsers.

The web is forever getting faster and faster but you obviously want your web pages to download as quickly as possible. Using super-high resolution images isn’t doing your or your user’s bandwidth (or patience) any favors. Image compression is a great tool and you need to strike a balance between image quality and image size. Most modern image manipulation programs allow you to compress images and the best way to figure out what is best suited for yourself is trial and error.