Zip files are files compressed to reduce the size of a file or folder, according to the File Info website. Zipping a file or folder makes it smaller and more convenient to transfer over the Internet, whether you're uploading the zip file or downloading it. PCs running Windows Vista and Windows 7 have a built-in utility to open, or unzip, zip files, including files zipped on a Mac computer.
Double-click on the folder containing the Mac zip file to view the folder's contents.
Double-click on the zip file. It will unzip automatically. Drag the unzipped file or files out of the folder to move them to another location. If you want to open the zip files in a particular location, skip this step and use the method in Step 3.
Right-click on the Mac-created zip file to unzip the files in a different location. Select “Extract All” from the menu that pops up and choose the location on your PC where you want to send the unzipped files. Click “OK.”