Facebook has announced that it is testing a new digital assistant to take on the likes of Apple's Siri and Microsoft's Cortana. Meet Facebook M.

According to VP of messaging products David Marcus, M is powered by artificial intelligence that is trained and supervised by people (perhaps a reassurance after some recent high profile warnings about the potential pitfalls of AI).

M is said to differ from its competitors in that it is able to "complete tasks" on the user's behalf. For example, Marcus says it will be able to purchase items, have gifts delivered to people, book restaurants, make travel arrangements and set up appointments. Rival services typically answer simple questions or guide you to a service that can help you complete the tasks, but fall short of doing that for you.

Unlike Apple or Microsoft, however, Facebook does not have an operating system in which to embed its digital assistant. Instead, the service will be embedded within the Facebook Messenger app. For now, though, it sounds like it isn't nearly ready for a public roll-out, with Marcus describing the service as being "early in the journey" of being built into an at-scale service.

Meanwhile, in more good news for Facebook, the firm's founder and CEO Mark Zuckerberg has announced that one billion people have used the social network in a single day for the first time ever. The milestone, which was hit on Monday, means that around one in seven people on Earth logged in at some point over the course of the day.