After almost an entire year of internal testing, Facebook finally rolls out search for mobile and desktop users. Now, users can search for their old posts or posts from people in their network from years back.

In a blog post, Facebook vice president of search Tom Stocky announced that the social network is expanding its search offering to allow users to search in free form.

Previously, users using the U.S. English version of Facebook could only search on Facebook Graph Search, which was launched in 2013, using a specific format. For instance, one can only search for "restaurants in Miami" or "friends who studied in UCLA who like scuba diving." With the new search expansion, users can now search for "Kelly's graduation" or "best pasta restaurant in Milan" or "Inception movie review."  

"You've told us the most important thing is being able to find posts you've seen before, and now you can," says Stocky. "With a quick search, you can get back to a fun video from your graduation, a news article you've been meaning to read, or photos from your friend's wedding last summer."

The new feature will be available for desktop as well as iOS and Android users, will be rolled out this week to all users of the U.S. English version.

Stocky says the search results will be kept relevant by pulling up only the posts made by the user's friends, pages and people they follow. To protect users' privacy, Stocky says users can only search for posts that were only available to them before the new search feature was introduced.

"Usually when you think about information retrieval, it's all about matching content to queries or content to intent," Stocky said. "But what we found is that on Facebook people care as much if not more about who is posting the content as they do about what the actual content is."

Search results will appear in a ranking based on an algorithm that combines factors such as the number of people that liked and commented on the post and the closeness of the users. For instance, a search result from a friend will rank higher in the search results as compared with a post made by a friend of a friend.

"We keep the content quality really high on this," says Rousseau Kazi, product manager of search.

The only exception, for now, is for posts that include hashtags. In this case, if a person searching for "Hunger Games reviews" includes #HungerGames, everyone else from around the world will have their hashtagged posts about Hunger Games shown in the search results.

Facebook has a lot to do to improve its search product before it can be considered up to par with Google's search engine, which anticipates what users are searching for in spite of misspellings or incomplete search phrases. Still, Stocky says search is a "long-term effort" for the social network and his team is working on providing better features for users in the future.