PPI stands for Pixels Per Inch. We recommend 300 PPI for almost all products, but on some of our larger fabric products we recommend 150 PPI. There are two reasons for this: (1.) A 300 PPI design file could be too large to upload for products such as beach towels (2.) On fabrics, 300 PPI, and 150 PPI often look the same because of the texture in the fabric.