My app ships images that were probably never optimized, and I want that fixed. First, inventory every image my app serves: static assets in the repo and, if my app stores user uploads, how those are served too. For each, note the format, file size, displayed dimensions, and actual file dimensions. Then fix what's wrong: 1. Convert images to modern formats (WebP, or AVIF where my stack supports it) with sensible compression, keeping originals untouched. 2. Resize images to the maximum dimensions they're actually displayed at. A 4000-pixel photo rendered at 600 pixels is waste. 3. Add responsive image markup (srcset or equivalent) where images serve across screen sizes, so phones don't download desktop-sized files. 4. Add lazy loading for images below the fold, but NOT for the hero or first visible image, which should load eagerly and have explicit dimensions to prevent layout shift. 5. For user uploads (if applicable): add server-side resizing and compression on upload so users can't upload a 12-megabyte avatar that gets served back at full size forever. Set explicit width and height (or aspect ratio) attributes on image elements so the page doesn't jump while loading. When done, report per page or component: weight before, weight after, and what changed.