OpenDNS is a service that lets you block all the computers in your house from accessing certain sites without having to install any software anywhere.
It’s free and easy and it works.
An “explain like I’m five” generalization of the service:
The internet doesn’t work in words (like google.com or facebook), everything is done using “IP Addresses”. If two computers want to talk, they need to know each other’s IP Address.
Normally when you are connected to the internet and you type “GOOGLE.COM” into your browser, your browser contacts your router, and your router contacts your internet service provider looks up “GOOGLE.COM” in a big spreadsheet and finds out that its IP Address is 22.214.171.124, and then your computer uses that to talk to Google.
The system that manages that big spreadsheet of which domain name is attached to which IP Address is called a Domain Name Server, or DNS.
There are lots of different places that have DNS’s. Most people by default use the one their ISP provides (if you have never changed any settings, this is what you are using now), but you can choose whichever DNS server you want to use.
The cool thing about a DNS is that you can alter it, so that if (for example) you go to STUPIDSITE.COM, instead of looking up STUPIDSITE.COM and giving you back the right IP Address, it gives you back a bad IP address so it fails and you can’t go to that page.
OpenDNS lets you configure your own personal DNS. They have categories like “porn”, “gambling”, “extremism”, “drugs” and so on, and they let you choose which categories to block. When you try to visit a page in one of those categories, it sends you instead to a web page that says “This page is blocked!”.
You sign up for a free account at OpenDNS, and then there are easy to follow guides there on how to set it up. You can change a really basic setting in your router to make any computer that’s hooked up to your internet (with a wire to the router or by wifi) use your OpenDNS settings instead of the normal ISP DNS.