An example of a JPEG with a nontransparent background, which will always be the case with the JPEG format.
Many people would like their JPEGs to have transparent backgrounds. For example, someone might want to "crop out" the climber in this photo, and have the graphic's background inherit the page background. (Like the GIF example earlier, so that the climber floats on the page.)
However, JPEGs cannot have a transparent background. This is one of their inherent limitations.
You can work around this if your page background is a solid color. If that's the case, use an image editing program (which we'll explain in more detail later) to paint the background the same color as your page.
But if your page doesn't have a solid background (like the illustration here), then the JPEG may not float on top of the background very seamlessly. You can either change the page background to be solid, or change to a file format that supports transparency.