AnHTML background image adds a visual element behind webpage content, helping create an attractive and engaging design. Although HTML defines the page structure, CSS is generally used to apply background images. You can add an image by setting the background-image property on an HTML element. For example, use body { background-image: url('background.jpg'); } inside a CSS stylesheet. You can also control image positioning, repetition, and sizing. For a full-page background, background-size: cover helps the image fill the available area. Always choose suitable images and maintain enough contrast so text remains readable.