Almost a year ago, Facebook transformed the search bar normally used to find other Facebook users into a tool for finding what those users were saying. The company indexed everyone's posts so you could see friends discussing Mad Max or the FIFA Women's World Cup by typing the phrase into the search box instead of waiting for the post to pop up in your News Feed. Starting today, the company is going one step further and indexing the entirety of Facebook's 2 trillion posts and making them searchable.

The decision turns Facebook's search function into something broader and more fascinating than a tool for looking up an acquaintance you met at a party. It's now a way to see what the internet is talking about in real time, in a way that only Twitter has ever mastered. Because Facebook commands the lion's share of our time spent online, it hosts a huge percentage of the links we share from around the web and the discussions we have around news, personal interests, and other moments in our lives. Facebook's search team is now turning that firehose of human interaction, which already generates 1.5 billion daily searches, into a vast repository of discussion, searchable by anyone.

Facebook contains 2 trillion posts and fields 1.5 billion daily searches

You'll now be able to search for something as broad as "MLB" and find a tailored, hierarchical list of Facebook posts. Starting with authoritative sources like news organizations, the search results will become more granular as you scroll down to what your friends are saying, liking and commenting on and then finally to strangers discussing the same topic. For the first time, you'll be able to easily find the posts of anyone discussing a certain topic anywhere, so long as that post is designated as public.

"Because we’ve indexed the entire world’s conversations, we tell you things that are trending, things that are breaking, what's happening right now," says Rousseau Kazi, a product manager on Facebook's search team. "The whole idea here is that if you can group these pieces of content in certain ways, it makes it pretty easy to get the full story."

Taking the incomprehensible mounds of text, photos, and links that users dump onto the web daily and turning it into something digestible and useful is the next logical step for our social networks. The task of making sense of the entire planet's social media musings is so complicated that Twitter essentially had to re-architect its entire user experience, leading to the creation of Moments. That new Twitter tab, launched earlier this month, is a way for you to more quickly grasp what's happening in the realms of news, live events, sports, and the various viral conversations raging across the network at any given time.

Facebook's search function offers a direct challenge to that service. It asks users not to head on over to Twitter to find out what's happening at any given moment, but to stay put on Facebook and search for it. "Once you understand the basis of the story, we move into how your world is reacting to it," Kazi says. "We’re making it super easy for you to get everyone's perspective in one place about a topic that you care about."

There is no new name or branding initiative to mark the change. Facebook search will simply be more powerful than it was before, starting first with everyone who designates English (US) as their primary language in the site's settings. The feature will be available for those users on iOS, Android, and the desktop version of Facebook, with a steady rollout over the next few days, the company says.

What sets Facebook search apart from other search engine is the way it is tailored to the individual user. Facebook says every single action you've taken on the social network, from who you've become friends with to every page you like, will inform the search results. (Google search results are also personalized, but draw on different signals, such as your emails and calendar entries.)

"We have to balance two things: how are the authors relevant to you and how is what they’re posting relevant to what you’re searching for," says Tom Stocky, Facebook's vice president of search. That means Facebook can tweak results depending on the type of query. If you search for Syria, Stocky says you'll more likely find posts from people who live in the country up top, followed by the post of a good friend in the US simply talking about a news story.

Of course, with any discussion of Facebook's growing repository of knowledge about its users comes questions about privacy. Until now, you've been able to post comments on articles without having to think about what consequences they might have years later, when someone found them through a search query. Kazi and Stocky mentioned a new feature with search that will let you type in a news event, like the 2012 US presidential election or the passing of Steve Jobs in 2011, and find popular news articles posted to Facebook from that time period and look at the comments posted there.

It's a fascinating idea — an enduring Facebook time capsule for any moment or event since the service's creation, searchable at any time. But it's also unsettling to think any shred of data on Facebook that was either made public on purpose or accidentally is now indexed and searchable. It also leaves open the possibility that Facebook advertising in the future is targeting you based not just on what web pages you visit before heading over to Facebook or what pages you like on the social network, but anything you've posted about throughout the existence of your Facebook account. Facebook says it's not introducing any new ad capabilities at this time.

Facebook can create enduring time capsules of public sentiment

Instead, Facebook wants people to be conscious of how they're sharing. "We’ve been proactively reminding people who’ve they been sharing with," Stocky says. Nonetheless, the team hopes the new search tools will result in more public posts — along with an improved reputation as a place to search for real-time news and conversation.

Facebook's new search tools will only be useful if people decide both to create more public posts and come to think of the search bar as a way to discover interesting posts. Both remain open questions. A previous Facebook effort to upgrade search — its vaunted Graph Search — withered into nothing. It may be that the latest upgrade is the thing that finally lets you use Facebook to take the pulse of the planet. In the meantime it's simply the social network's latest reminder that nothing you post there ever really goes away.