Social networking giant Facebook on Thursday said it had started to test a new service called 'M' which is a digital personal assistant inside the messenger app."Today we're beginning to test a new service called M. M is a personal digital assistant inside of messenger that completes tasks and finds information on your behalf," the company wrote in a blog post."It's powered by artificial intelligence that's trained and supervised by people. Unlike other AI-based services in the market, M can actually complete tasks on your behalf. It can purchase items, get gifts delivered to your loved ones, book restaurants, travel arrangements, appointments and way more," it added.The addition of M in the market will add to the existing kitty of personal assistants which include Cortana from Microsoft, Siri from Apple and Google Now from the internet giant's stable."This is early in the journey to build M into an at-scale service. But it's an exciting step towards enabling people on messenger to get things done across a variety of things, so they can get more time to focus on what's important in their lives," the company said.