Lossy vs Lossless Compression
Lossy trades some detail for much smaller files; lossless keeps every pixel.
Lossy compression (JPEG, WEBP, AVIF) discards information the eye barely notices to achieve small files — ideal for photos. Lossless compression (PNG) preserves every pixel exactly — ideal for graphics and text.
Compress lossily to an exact size with Reduce Image Size in KB, or keep transparency losslessly with JPG to PNG.