Digital ProductionRevised
Raster
A pixel-based image format whose detail is fixed at capture or creation.
In practice
A raster image is a grid of pixels, each holding one color, like a mosaic. Photos, scans and painted digital artwork are rasters, and their detail is fixed: enlarge them beyond their pixel count and edges turn soft or blocky. A website's main photo is a raster file chosen at a size large enough for wide screens. Common raster formats include JPEG, PNG and WebP; a camera's RAW file is a special unprocessed case.
Often confused with Vector File
A raster stores a grid of pixels with fixed detail; a vector file stores shapes as mathematical paths that stay sharp at any size.
Try this
Zoom a photo to 800 percent until its pixel grid appears, then zoom a vector icon the same amount and compare.