Artwork files come in two fundamental types: vector and raster. Understanding the difference is the single most useful piece of knowledge for anyone ordering custom apparel.

Vector files (AI, EPS, SVG): Built from mathematical paths, not pixels. They scale infinitely without quality loss. A vector logo prints at 2 inches or 20 inches with identical clarity. These are the gold standard for apparel.

Raster files (PNG, JPG, TIFF, PSD): Built from pixels. They have a fixed resolution. Scaling them up degrades quality. JPG is the most common and the most problematic: compression artifacts destroy fine detail.

PNG with transparency is the best raster format for apparel. No compression, supports transparent backgrounds (critical for printing on colored garments), and preserves crisp edges better than JPG.

PDF can contain either vector or raster data depending on how it was created. A PDF exported from Illustrator is vector. A PDF generated from scanning a document is raster. Don't assume a PDF is print-ready.

The hierarchy: AI/EPS > SVG > High-res PNG > PDF > PSD > JPG. Send the highest quality format you have.