Use JPG images for photographs and other images that have millions of colors.
It uses a complex compression algorithm that allows you to create smaller graphics by losing some of the quality of the image.
This is called a "lossy" compression because some of the image information is lost when the image is compressed.
The JPG format is not suited to images with text, large blocks of solid color, and simple shapes with crisp edges.
This is because when the image is compressed the text, color, or lines may blur resulting in an image that is not as sharp as it would be saved in another format.