Turn a relay on and off using a push button. When using a pushbutton, you have use a library (don't reinvent the wheel) to control the push button signal. It's called a debounce, taking account in...
A microcontroller is a small computer on a single integrated circuit containing a processor core, memory, and programmable input/output peripherals. Microcontrollers are designed for embedded applications, in contrast to the microprocessors used in personal computers or other general purpose applications.