Facebook is publically testing a new News Feed feature that shows you what your friends were up to in years past on this day. The "On This Day" tab is in beta on both the web and mobile for select users with the most up-to-date version of the social network.

Those using the web version of Facebook may notice the option by clicking the down arrow beneath the News Feed categories found in the upper right-hand corner of the page. Doing so will launch a header image from a past photo or gallery upload in addition to showing more content from the past.

TNW points out that highlighted posts and status updates aren't assembled in chronological order. This could be simply because Facebook is beta testing the feature or perhaps the social network is using some type of complex algorithm that selects only the most interesting content to keep users engaged with the new feature.

The feature is also available to select mobile users. Using the iOS app, scroll to the top of your News Feed and look for the tab via the expandable menu. You'll get a similar experience to what you would find on the web although we are told the posts and content are arranged in a different order.

It's an interesting feature designed to keep users on the site for longer periods of time by offering them a trip down memory lane although it isn't entirely an original idea. Facebook launched a similar feature, also known as "On This Day" back in August 2011. It's unclear, however, why they killed the feature back then.