This week Apple Apple released iOS 10.3.3 and its highly recommended that you apply the update as soon as you are able. You can read the details of the update here in the Technical Bulletin.
In short, it contains security updates that protect your device from not only malicious websites but from an ugly vulnerability in your WiFi. The update prevents someone from hacking directly into your phone through the WiFi radio! Pretty scary stuff!
To manually update go to Settings > General > Software Update and choose Download and Install.
Stay cyber-safe out there!