All of Pfoinkle's free digital stamps are provided in two file formats: .jpg files with an opaque (white) background and .png files with a transparent background. All files are downloaded as part of a ZIP file.
About Zip Files
All free digi stamps are downloaded in "zip files." A zip file contains multiple files (such as several graphics) and must be "unzipped" to access the individual files. If you've never unzipped a zip file before, here are the instructions for Windows Users and for Mac Users.