| PoE stands for Power over Ethernet, which is a way of passing data and power via a standard Ethernet cable.
What is a PoE injector?
PoE injectors 'inject' power into an RJ45 Ethernet cable along with your usual data (internet connection), which you can then 'split' back out at the other end using a PoE splitter or PoE HAT.
Why would I use PoE?
PoE is really handy for removing the need for a wall socket where your end device is, giving you both wired internet and power in awkward locations via a single cable.
It's also a popular choice for those running multiple devices/Raspberry Pi, as it removes the need for lots of individual plug sockets and power supplies (a PoE switch as an injector is generally the better option here).
What else do I need for PoE?
You're also going to need an RJ45 Ethernet cable between your injector and splitter, and of course, a splitter.
In our Raspberry Pi-focussed world, splitters come in two flavours - as a PoE HAT, or a standalone splitter giving you a separate USB-C/Micro-USB cable and an Ethernet cable. | 
