Most versions of Windows and MacOS (as well as iOS devices such as iPhones and iPads) have encryption built in but it just needs to be activated.
Encryption keeps your data secure if the laptop is lost or stolen as without the password it's impossible to access the files on the disk. Without encryption, even if you have a login password, someone could remove the hard drive and connect it to a different computer to gain access to all your files and data. Encryption stops this from being possible. If someone was to remove an encrypted disk and connect it up they will not see any of your files.
The links below are to PDF documents showing the steps involved in turning BitLocker encryption on for Windows computers, FileVault encryption for Apple Macs and also how to check your iPad/iPhone is encrypted.
For Windows computers you can follow this PDF guide to encrypt your hard drive using the BitLocker system.
For Apple Mac computers you can follow this PDF guide to encrypt your hard drive using the FileVault system.
For iPhones and iPads you can follow this PDF guide to turn on iOS encryption.
The procedures are usually straight-forward but if you run into any problems and need further advice you can contact the College IT Office at firstname.lastname@example.org