4.2 Arduino Uno
The Arduino Uno is probably the most popular thing you have never heard of. The community around this little micro-controller is huge. It was designed in Italy to teach students how to code a micro-controller.
With it you can easily receive data from sensors, you can control LEDs, motors and connect to displays. It uses very little power and you can even make one yourself. Although it is created by Arduino it is open source so anyone can make one and sell it. That is why if you go on eBay you will see 100s of copies which are perfectly legal.
You code it in C++. This is a slightly lower level language than say Python (which is a high level language). The lowest level is binary which is a series of 1’s and 0’s. When you type in your code it is converted into a language the micro-controller can actually use.
Don’t let this put you off, C++ is where I started learning to code and is my favourite for that reason. You could use this if you are interested in making a robot or some gadget. It cannot store a lot of memory but it does work quickly.
If you like to switch LEDs on/off, read sensors, play with motors or explore different displays then this is where I think you should start. Arduino have a wonderful website where you can download the free IDE (the software you need to type your code in) so that you can talk to the Arduino.
The website is full of resources to help you and the internet is full of solutions, ideas and suggestions. When you start looking you won’t know where to stop. It the most fun (coding) for very little money.