A VPN client is software that runs on your device to connect it, securely, to a VPN server. All major platforms (Windows, macOS, Android, iOS, and Linux) come with a built-in VPN client that can be configured manually, although OpenVPN always requires a third-party client to be installed. Most VPN providers will now offer custom clients and apps that are the easiest way to use the service, seeing as they come pre-configured with all the right settings. What's more, they also offer a range of funky and useful features that are not available by simply manually configuring the built-in VPN client. To clear up any confusion, a ''VPN client'' and a ''VPN app'' are exactly the same thing. Traditionally, the word client is used for desktop software and the word app for mobile software, but it is becoming increasingly common to talk about VPN apps on the desktop. The terms are interchangeable.