Vector vs raster
Vector art is built from math — points, lines, and curves — and scales to any size without losing sharpness. Raster art is a fixed grid of pixels and gets blurry or jagged when enlarged past its native resolution.
Why it matters
You hit this every time you scale a logo. SVG logos stay crisp at any card size; a small JPEG dropped into a poster falls apart fast.
Example
An SVG icon scaled from 24 px to 600 px stays razor-sharp. A 24 × 24 PNG of the same icon scaled to 600 px becomes a pixelated mess. PDFs can hold both — vector for text and shapes, raster for photographs.