1. Investigations by the special counsel: The Russian government's attack on the 2016 election

Russian leader Vladimir Putin. Adam Berry/Getty Images

What we know: The best-known investigation headed by Mueller and his team has looked into the Russian government's attack and interference on the 2016 election. This investigation is looking into data theft, the rigging of the US voting system and information influence operations by the Internet Research Agency.

What has been done: So far, Mueller has indicted 12 Russian intelligence officers, 13 Internet Research Agency workers, as well as three Russian companies and a man from California who aided their identity theft.

What comes next: We have yet to find out, among other things, whether any Americans knowingly contributed to the attack and the level of involvement by Putin himself.