Facebook has begun rolling out a new feature dubbed Nearby Friends which will help users know which of their friends are nearby.

Nearby Friends is an opt-in feature and helps users find out how close they are to their friends’ locations. This feature was developed by a team led by Andrea Vaccari and they have been working on it since 2012.

Nearby Friends makes a list of those friends who have opted in and adds the list to the iOS and Android apps. When a friend intentionally shares their location with you and you reciprocate it, you can see the distance between your locations in addition to a map showing you the directions when they share the exact location.

Vaccari said to TechCrunch, “the idea is to make it really easy to discover when someone is around you, and meet up and spend time together”.

Though the idea sounds similar to the services of Foursquare, Google Latitude and the several other location sharing features, the main purpose of Nearby Friends is to let users share the distance between them rather than the location.

The reciprocal privacy model upon which the feature is built lets users to know the distance only when they deliberately opt to share the information with each other.

Keeping the feature turned on is said to cause battery drain and Facebook’s tests revealed that it causes a drain of about 0.3 to 0.4 percent drain in battery charge per hour. This feature is available only to users who are over 18.

The feature also lets users decide for how long they want to share their location information and to which friends or lists they want to share it with. It also lets users send a 40-character long message to communicate with the friends they share their location with.

Facebook has said Nearby Friends feature will not be used for ad targeting, at least for now.