Vector vs raster: what is the difference?

Every digital image is either a raster (pixel-based) or a vector (math-based). Knowing which is which solves most 'why does my logo look blurry?' problems. Here is the plain-English version.

• Raster graphics: A raster image is a grid of colored pixels. Each pixel has a specific color, and the image has a fixed resolution. Common raster formats include JPG, PNG, GIF, BMP, TIFF, and WebP.
• Made of pixels arranged in a grid
• Has a fixed resolution (e.g., 1920x1080)
• Pixelates or blurs when scaled up
• Best for photographs and screenshots
• Vector graphics: A vector image is described mathematically using points, paths, curves, and shapes. There are no pixels, the image is recomputed every time it is rendered, at any size. Common vector formats include SVG, EPS, AI, PDF (when vector content), and DXF.
• Made of mathematical shapes and paths
• Resolution-independent, scales infinitely
• Best for logos, icons, illustrations
• Editable shape-by-shape
• When to use raster: Photographs, complex natural imagery, screenshots, and anything where you need exact pixel-level color information.
• When to use vector: Logos, icons, brand marks, illustrations, charts, diagrams, signage, packaging, and anything that needs to scale or be edited later.