What is the 50 30 20 wealth rule?

Could you elaborate on the 50 30 20 wealth rule and its relevance in the world of cryptocurrency and finance? I've heard it mentioned in various financial circles but am unclear on its specific application and benefits. Could you break it down simply for me? I'm particularly interested in understanding how it could potentially aid in the allocation of funds across different assets, including digital currencies, and how it might help with long-term financial planning.