Vector vs raster.

Two ways a file stores a picture. Custom Ink puts it plainly: a raster image is a grid of coloured pixels, a vector image is defined by mathematical paths, and a vector has no fixed resolution, so it scales from a business card to a billboard while a raster blurs or blocks as it grows. Custom Ink lists .ai, .eps, .pdf, .svg and .cdr as vector types and .jpg, .png, .gif, .psd, .tif and .bmp as raster, with its own floor at 200 DPI at print size. The extension does not settle it. A PDF, EPS or SVG can carry nothing but an embedded photo, and that file is still raster under a vector name. The difference decides the process: cutters for heat-transfer vinyl and screen-printing separations want paths, because a blade and a spot screen follow edges, while DTG, DTF and sublimation print pixels either way. A pixel logo sent where paths were expected comes back either redrawn as a vectorisation job, or cut along a stair-stepped edge that follows every pixel.