Previously if you blocked someone on Twitter, their tweets could still be retweeted by another user into your timeline.
The micro-blogging site is adding a total block to combat trolls and abusive behaviour.
Twitter called it a powerful tool to restrict people from contacting you or seeing your tweets when logged in.
"When you block someone on Twitter, they cannot follow you or send direct messages. If they @ mention you, you will not see a notification," Twitter said.
Because Twitter is a public platform, if you search for a user through a search engine when not logged in, you will still be able to see their account.
But if you block a user, they won't be able to interact with you in any way on your account.
The firm's also made one other big change.
You can now retweet yourself if you want to.