Lossy vs Lossless Compression
Two compression approaches: lossy permanently discards some data for smaller files; lossless preserves all original data.
JPEG is the most common lossy format — it discards fine detail that the eye is unlikely to notice, achieving file size reductions of 10-20x. PNG and TIFF use lossless compression, preserving every pixel exactly but producing larger files. For editing workflows, work in lossless formats and only convert to lossy JPEG for final delivery where file size matters.