What is an 'everything app' and why does Elon Musk want to make one?

On Tuesday, Elon Musk announced he would go ahead with his original $US44 billion bid to buy Twitter. A super app, or what Mr Musk refers to as an "everything app", has been described as the Swiss army knife of mobile apps, with a suite of services including messaging, social networking, peer-to-peer payments and e-commerce shopping. Chinese super app WeChat has more than 1 billion monthly users, according to one estimate. In a question-and-answer session with Twitter employees in June, Mr Musk said he saw an opportunity to make an app like WeChat. Adding more tools and services to Twitter could also help the billionaire reach his lofty goal to expand the app's number of users from 237 million to "at least a billion".