What is the general protocol to send information from one system to another? For example, let's say we have some information collected from microcontroller over a length of time that we want to send to another microcontroller. I've heard of SPI and I2C interfaces, but I am unclear when you use one method over another and how you implement it. Are there other methods besides SPI and I2C that are common? Is the implementation process similar for different microcontrollers? Is it basically parsing bytes of data that I am doing on the receiving microcontroller?