I2C
Contributors:
SFUptownMaker
SFUptownMaker 
Introduction
In this tutorial, you will learn all about the I2C communication protocol, why you would want to use it, and how it's implemented.
The Inter-Integrated Circuit (I2C) Protocol is a protocol intended to allow multiple "peripheral" digital integrated circuits ("chips") to communicate with one or more "controller" chips. Like the Serial Peripheral Interface (SPI), it is only intended for short distance communications within a single device. Like Asynchronous Serial Interfaces (such as RS-232 or UARTs), it only requires two signal wires to exchange information.
Suggested Reading
Stuff that would be helpful to know before reading this tutorial:
Serial Communication
Asynchronous serial communication concepts: packets, signal levels, baud rates, UARTs and more!
Serial Peripheral Interface (SPI)
SPI is commonly used to connect microcontrollers to peripherals such as sensors, shift registers, and SD cards.
Binary
Binary is the numeral system of electronics and programming...so it must be important to learn. But, what is binary? How does it translate to other numeral systems like decimal?