Twitter announced today that it will now allow advertisers to tailor ads for you based on your activities off of Twitter (for instance, browsing third-party websites), and will also use personal information like email addresses to target the ads you see.

"Users won't see more ads on Twitter, but they may see better ones," wrote Twitter's Senior Director of Product and Revenue, Kevin Weil, touting the change as a way to make the service "more useful" to users.

Privacy-minded folks won't be too happy.

Advertising Age has more. A positive note for privacy advocates: Twitter offers you opt-out with this stuff; Facebook doesn't.

As Twitter's official announcement explains, you can avoid the increased tracking/targeting by simply checking off a couple of boxes in your Account Settings, and by enabling Do Not Track (DNT, not DMT) in compatible browsers.

Here's how to opt out, if you are so inclined:

1) Log in to your Twitter account.

2) Under "Settings," uncheck the boxes shown above.

3) Enable "Do Not Track" in your browser (FF, Chrome, IE are all compatible).

4) Follow @boingboing. Hah, I made that part up! But please do.