Raster File
A file made of pixels — JPG, PNG, GIF. Quality degrades when scaled up.
Raster (or "bitmap") graphics are made of pixels arranged in a grid. The most common raster formats are .jpg, .png, .gif, .bmp, and .tif. When you zoom into a raster image, you eventually see the individual pixels — the "blocky" effect.
Raster files are fine for printing, but only at the resolution they were created. A 300 DPI raster image at print size will look crisp; the same image scaled up 200% will look blurry or pixelated. For DTG and DTF, raster files are the standard input format.
Avoid taking a small raster file and scaling it up to print large — the quality will not be there. Instead, source a higher-resolution version of the image, or recreate it in vector if it is a logo or simple graphic.