GitHub already said they liked the idea of a takeover by Microsoft more than an individual IPO. The last time GitHub was valued it worth was 2 billion US dollar.
GitHub is dealing with some serious problems, it has never made a profit and they are missing a CEO for almost 8 months. A takeover by Microsoft could be a huge boost for GitHub.
GitHub is a development platform in which developers can share their code with their teams or with other people in repositories.