Time-variation of fundamental constants

Fundamental constants are very important numbers that tell us a lot about how the universe works. They never change, but over time, they can appear to change slightly. This is called 'time-variation' of the constants. It's like when your family decides one day to move the furniture around in your house- it still looks like your house, but things appear to be a bit different! It's the same with fundamental constants- they don't actually change, but their values may appear to be a bit different over time.