L2TP/IPsec (Layer 2 Tunneling Protocol with Internet Protocol Security): L2TP is not secure itself, so it's generally paired with the IPsec secure-networking standard. The combination of the two was once thought to be very secure when properly implemented, but some VPN services suggest that you use OpenVPN instead. L2TP/IPsec has native support in Windows, OS X/macOS, Android, Chrome OS and iOS. Most VPN services support it.
With hundreds of VPN services and clients available, it can be difficult to decide which one to use. We've extensively tested several popular VPN services that met three requirements: They had both desktop and mobile client software (with one exception), they had VPN servers in many countries, and they offered unlimited data use, at least in their paid versions.
Are you so used to your data traveling over Wi-Fi that you've stopped worrying about the security of that data—and about who else might be spying on it, or even stealing it for nefarious purposes? If so, you are—sadly—in the majority, and you ought to consider using a viritual private network, or VPN. In fact, when PCMag conducted a survey on VPN usage, we found that a dismal 71 percent of the 1,000 respondents had never used a VPN. Even among those who support net neutrality—who you might think would tend to be well informed on technology and privacy issues—only 45 percent had used a VPN.