What is the difference between raster and vector artwork?

Raster artwork, like photos and Photoshop files, is made of pixels. Enlarge it too much and it gets blurry or blocky, so it needs enough resolution for the final print size.

Vector artwork, like logos and illustrations built in Illustrator, is made of shapes defined by math. It scales to any size without losing quality, which makes it ideal for big signs and banners.

One catch: effects in Illustrator, like drop shadows and glows, are raster even inside a vector file. Set Effect > Document Raster Effects Settings to a high resolution before you export, or your shadows can come out pixelated on a big print.

If your logo only exists as a small JPG, ask your designer for the original vector file, or have it redrawn as vector before you print it large.