Image compression reduces the size of an image file so it uploads faster, loads quicker and takes up less storage.
There are two kinds. Lossless compression (PNG, some WebP) rebuilds the image exactly, with no quality loss. Lossy compression (JPG, most WebP) discards fine detail your eye is unlikely to miss, which makes files dramatically smaller.
Compressing images is one of the biggest wins for a fast website and for staying under email or upload size limits.
Try Compress Image to shrink a JPG, PNG or WebP without a visible drop in quality.