Compress vs Resize an Image
These terms are often confused. Compression changes how much data is stored per pixel; resizing changes how many pixels exist. Both reduce file size — differently.
When to compress
Keep dimensions, lower quality or re-encode. Best when the image is already the right size but the file is too heavy.
When to resize
Reduce width/height. Best when the image is physically too large (4000px wide for a 800px blog slot).
Best workflow
Resize first to target dimensions, then compress. Often beats compression alone for huge camera photos.