ELI5 Moon Drift - why it's moving further away each year?

Why is the moon slowly moving away from the earth at 4cm per year? How do we even measure it so precisely? Why does the same side of the moon always face the earth? What is the beautiful dimensional coincidence that gives us a a perfect solar eclipse?

... We explain like i'm five!

Thank you to the r/explainlikeimfive community and in particular the following users whose questions and comments formed the basis of this discussion: deletedscenebrowser, mobius1424, joldz, smlz101, puppypile99 and boymcmoyo

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