To activate file compression on a file or folder:
- Right-click the item you want to compress, and select Properties.
- Press the Advanced button at the bottom of the dialog.
- Check the 'Compress contents to save disk space' checkbox, and press the OK button twice.
- You will then be prompted to choose to apply the compression to just a file or folder (which includes any subfolders and files within it), then press the OK button to continue.
Note: Avoid trying to compress files that are already compressed (such as: audio, image, and video files), this can sometimes create files that are larger then the original.