"A zip file takes a directory of, say, 25 files and makes it into one file," Samir Khuller, chair of Northwestern Engineering’s Department of Computer Science, tells Popular Mechanics.

How does a zip file work, and how can you use it? Here's everything you need to know to master the art of sending massive files.

Have a private document on your desktop OS? Here's how to keep it secure on Linux, MacOS, and Windows.

Next, select Encrypt a non-system partition/drive and select Next. Select the drive you want to encrypt and follow the instructions on the screen.

Express Zip free file compression for Windows lets you open & extract archive formats like zip, rar, cab, tar, 7z, iso, gzip, multidisk, zipx, lzh, arj & more.

Whether you use Windows Pro's built-in Bitlocker or the free Veracrypt utility, encrypting a file, folder, or drive is an easy way to keep your sensitive documents secure.

Save space on your Mac by compressing pictures, videos, documents and folders into smaller zip files - which you can also protect with a password ...