Due to its rugged nature, the Infinity:One hides many of its ports (including the charging port) underneath a pull out flap - as pictured below.
Once you slide the flap out and up, a number of ports are revealed.
From right to left:
For connecting to smart boards, TVs and other screens.
For playing audio through a standard 3.5mm jack.
This is a multipurpose port that supports standard micro-USB cables.
The bottom port when the Infinity:One is held vertically, this one charges it up!
The keyboard dock has one more very important port:
This is your standard USB port, for plugging in USB sticks, mice, or anything else with a standard USB plug.