How to Block Websites on Your Mac
Many web browsers offer plugins to help you stay productive, and not open the websites you waste time on, but you can take things one step further by simply blocking your computer from accessing specific sites all together.
This is why I recommend editing the Hosts file on your Mac, using Terminal. Yes, it looks a little intimidating, but once you get the hang of it, you'll have banned those websites across all browsers, and doing so without relying on a plugin that may lose support when its developer grows tired of updating it.
The below steps were performed on a MacBook Air running macOS High Sierra (10.13), but they should work the same on all Mac from the last decade or so.
1. Click the magnifying glass in the top right corner. If it's not there, hit Command+Space.
2. Type "Terminal"
3. Select Terminal.
4. You've reached the command line, it's a little intimidating, but don't worry.
5. I'm going to give you a series of commands to type in, and each will have quotation marks on the front and back, which you should ignore.
6. Type in "sudo nano /etc/hosts"
7. Hit Return.
8. Type your system admin password.
9. This is the host file database, tap the down arrow to move your cursor below the line that says "127.0.0.1 localhost"
10. Type in "127.0.0.1 " and then the address of the site you want to block, making sure to keep a space between the numbers and the address. For example, "127.0.0.1 facebook.com" will block Facebook.
11. Hit return.
12. Type in "127.0.0.1 " followed by that address with the "www." prefix in front of it, for extra measure. For example, "127.0.0.1 www.facebook.com"
13. Hit return.
14. Click Control + O to save your change.
15. Click Return.
16. Click Control + X.
17. Type "sudo dscacheutil -flushcache"
18. Hit return.
Now, when you open that website, in any browser on that Mac, you'll get a message that says you're unable to connect.