Twitter recently introduced a much welcomed update: the ability to reply to tweets without cutting into your 140 character count. So when you respond to someone's tweet, the username will no longer eat into your character count.

This is particularly great for having conversations with people with really long Twitter usernames. It only works, however, if you hit the reply button on a conversation. If you start to type someone's username in a new tweet, it will still count toward your 140 character limit.

Here's how it works. When you hit the reply button on a conversation with several people, you'll see their usernames above the text box.

You can click or tap the list of names to pull up the full list and remove people from the conversation if you want, write your tweet, and hit reply.

While this is a handy little update, it does have one significant downside.

Let's look at a possible scenario. Two people are having a heated conversation on Twitter. A third person replies to one of their tweets, a fourth person replies to the third person, ad infinitum, and suddenly there's 20 people tweeting in one conversation.

Thankfully, for the sake of your sanity and notifications, you can opt out of the conversation. Go to your replies and click the arrow in the upper right corner of the tweet and select Mute this conversation.

What do you think of Twitter's latest update? Let us know in the comments.