DO is what is liked
IO is “Liked by who?”
I like the food
You like the cars
Me gusta la comida
DO = la comida
IO = Me
Te gustan los coches
DO = los coches
IO = Te
Add prepositional phrase for clarity
He likes the food
A él le gusta la comida
Two forms of gustar used based on the plurality of the DO
I like the tree
I like the trees
Me gusta el árbol
Me gustan los árboles
Add prepositional phrase for emphasis
Margarita likes tea
I like coffee (emphasize contrast)
A Margarita le gusta el té.
A mí me gusta el café