We archive all our collections in order to make them smaller for download. We use an application that creates a .zip file. In order to unarchive your collections, you will need a .zip expander application on your computer. Commonly your system has an expander application built in to it and you can double click on the .zip file and it’ll open automatically. If not you can go online and download free versions of Stuffit Expander for the Mac and Unzip for the PC.