Hi,
First, I used designing my controller circuits (hardware) using transistors, resistors and capacitors only.
Then I was glad that digital ICs (as the series 7400) were introduced because I was able replacing too many transistors and RCs by one small equivalent IC.
Soon later, my hardware became full of digital ICs (gates, timers, memories, multiplexers, adders... etc).
Now I have the choice to use a single IC as a microcontroller (MCU) in which all the previous digital ICs are, even much more
Almost all pins of an MCU IC are just input/output ones. Yes it is as simple as this. So if a pin is set by software as output, an instruction can set this pin as high or low (close to Vcc or 0). Otherwise it can sense a low/high voltage and an instruction can read it (and save it in an internal register).
The beauty of using an MCU for example is that many features of the controller can be changed or updated just by playing (to me it is like a game) with its simple software codes (using an assembler or a high language as C). I prefer the former since it is closer to the hardware I used to play with in the past so I can take advantage of all parts and features included in the MCU while using simple basic instructions.
In my opinion, your hardest step for you is to let your first MCU control the on/off of an LED for example. After this basic step, you will find yourself invited to a new world in which your mind will keep creating new boards for fun and for serious applications as well
Wish you good luck... but you have to be patient
Kerim