data providers and mixins basics?

Looking at making an minimap/map addon and some of the example code(s) I'm looking at use data providers and mixins. was wondering if anyone could give their opinion on the "philosophy" of using them, examples of use, why use them over XYZ, etc.

I.E. , what are the basics of using data providers and mixins? Tbh, I never noticed their use before in wow addons and am wondering if this a newer paradigm consider the new "best practice"