A PDF sewing pattern is a sewing pattern you buy online and is sent to by email. Depending on where you purchase the pattern, it will either come to you as an email attachment or a link to a page where you would open the document and then save it to your computer. Once downloaded, you can print it out on your home printer using regular ink and letter paper for domestic or A4 for international customers. You then piece the pattern together with tape or glue and cut out as you would a normal pattern. Often PDF sewing patterns have a better fit than paper patterns from large companies due to the many hours put in testing the pattern out on various sized children or adults to get the fit just right. Most PDF sewing patterns are designed by independent pattern designers and support small business.