Compression is where most of the practical value in image work sits: a page that loads in one second instead of four, an attachment that actually sends, a form that finally accepts your upload.

These articles explain how lossy and lossless compression differ, what quality settings actually do, and why a "compressed" PNG sometimes comes out larger than the original. They also cover the everyday tasks — hitting a 100KB limit, preparing images for email, shrinking a PowerPoint deck, batch-processing a whole folder — with concrete byte budgets rather than vague advice. If you only read one, start with the target-size guide; it solves the most common problem.