Vector File
A digital image built from geometric paths rather than pixels, which can be scaled without losing quality.
In practice
A vector file describes an image as points, lines and curves defined mathematically, along with their fills and strokes. Because the shapes are recalculated at every size, one file can print a logo on a pen and on the side of a truck with equally clean edges. Designers create logos, icons, type and technical drawings as vectors, then export raster versions when a screen or platform needs pixels.
Often confused with Raster
A vector file scales cleanly because it stores shapes; a raster stores fixed pixels and loses quality when enlarged.
Try this
Draw the same simple shape as a vector and as a painted raster, enlarge both tenfold, and compare their edges.