To compress files for sending via email, you can use a variety of free file compression software. Popular programs include WinRAR, 7-Zip, and WinZip. All three programs allow you to create archives that can reduce large files into smaller ones, making them easier to send via email. You can simply select the files you want to compress, right click on them, and choose the “Compress” option. Once the files are compressed, you can attach them to your email and send them off.