What is it called when an image has no background?

When an image has no background, it means that the image has a transparent background. A transparent background is a feature of digital images that allows the background to be removed, making the objects within the image appear as if they are floating on a clear, see-through background. Transparent backgrounds are commonly used in graphic design, web design, and other digital media to create logos, icons, and other graphics that can be easily placed over different backgrounds without the background color or design interfering with the overall aesthetic of the image. The most common image file formats that support transparent backgrounds are PNG and GIF, although some other formats including TIFF, PSD, and PDF may also support them.