Nick Huntington-Klein (CSU Fullerton) has created a series of excellent gifs to illustrate what various causal inference methods do to data and how they work. The whole thread on Twitter is worthwhile, specially because learning these econometric methods becomes much easier once we have a solid understanding of the concepts and intuitions behind them. (Thanks Bernardo Furtado for the tip).
obs. Nick created these gifs in R using the gganimate package and the code is available here.
Here's the gif that shows the intuition behind difference-in-differences
