Sometimes you want just want to acknowledge a friend... make contact perhaps or just recognise their existence but you don't really have anything to say. Face to face you might just smile, nod or say "Yo", and that's the thought behind a new social network that's starting to go viral.

It's a simple app that allows you to send only one thing to your friends: "Yo".

According to Techcrunch: "Yo currently has over 50,000 active users, after launching as a joke on April Fools’ Day. Users have sent over 4 million Yo’s to each other. Without ever having officially launched, co-founder and CEO Or Arbel managed to secure $1.2 million in funding."

It's dead simple to use and free to download.

You're probably scratching your head and asking "why?"

But so did many people regarding Facebook, Instagram and Snapchat, which are all now well established social networks.

Internet pioneer turned venture capitalist and founder of Netscape Mark Andreesen says to think of "Yo" like the missed call phenomenon.

Remember before mobiles when you wanted to contact a friend but didn't want to incur the cost of a call, and you'd ring once and hang up. That would let them know you're running late or on your way or some other pre arranged message.

Currently in many Asian and African countries the missed call strategy of communication is strong. In Bangladesh about 70% of mobile calls are missed, people are mainly using this strategy as a way of communicating rather than paying for a call.

His point is that "one bit communication" using apps like Yo could serve a useful social purpose and are worth paying attention to.

(You can follow the author Jason Smith on Yo by adding username JASONSMITH)