Sometimes you want to e-mail someone several files - for example you have 15 photos, a PDF, and a word document, and you don't want to attach each one individually. An easy way to do this is to compress (zip) your files together. A ZIP file, like other archive file formats, is simply a collection of files, compressed into a single file to make it easier to send and make the file smaller. Once you have created a ZIP file, you can attach that one file, send it along, and the person receiving it can quickly open it and access all the files. Learn how to zip multiple files together, and unzip a file, in Windows. Remember - never open a file that you receive via e-mail unless you are expecting it (even if it is from someone you know) - it could contain a virus!