There are three main areas to consider when starting to understand the infrastructure.
The Crazyflie family of devices
The Crazyflie family members are the Crazyflie 2.0 nano quadcopter, the Crazyflie 2.1 nano quadcopter, the Crazyflie Bolt quadcopter controller and the Roadrunner UWB positioning tag. They are all based on similar hardware but have a bit different flavours and properties. They run similar firmware and can be used with the other components in the Crazyflie ecosystem, such as clients and positioning systems.
Crazyradio and clients
The main client for controling the Crazyflie device family is the python client that runs on a PC and communicates via the Crazyradio PA USB dongle. The client uses a python library, which also is the main connection point for programs and scripts that communicate with the devices.
Swarms of Crazyflies can be controlled through the python library, the external CrazySwarm project or other software.
There are mobile phone apps for Android and IOS that connects via BLE, mainly for manual flight.
Positioning support is needed for automated or autonomous flight. There are two in-house position systems in the Crazyflie ecosystem: the Lighthouse positioning system that uses SteamVR Base Stations and the Ultra Wide Band based Loco Positioning System. It is also possible to integrate with external positioning systems, for instance Motion Capture systems.