What is Variable Valve Timing?

I've heard that the BMW M4 has Variable Valve Timing, can you explain what this means?

Variable Valve Timing, or VVT, is a technology that allows for the precise control of the timing of the engine's intake and exhaust valves. This results in improved engine performance and efficiency, as well as reduced emissions.

In simpler terms, VVT helps optimize the combustion process in the engine, resulting in more power and better fuel economy. It's definitely a valuable feature in the BMW M4.