caer
Caer is 'to fall' — but in Spanish it also expresses how you feel about people, whether things suit you, and moments of realisation.
caer (fall)
Physical falling and things dropping, figuratively and literally.
Se cayó por las escaleras.
He fell down the stairs.
Caerse (reflexive) for the fall itself. Caer is the base verb; caerse emphasises the whole event.
Se me cayó el móvil.
I dropped my phone.
The phone fell from me — accidental drop uses this reflexive construction. Very natural.
La noche caía despacio.
Night was falling slowly.
Literary use of caer for time/light. Night, dusk, silence can all 'fall' in Spanish.
caer (impressions + expressions)
How people land with you, things clicking, and idioms built around falling.
Me cae bien / mal.
I like / don't like him (as a person).
Caer bien/mal = to make a good/bad impression. This is how you express friendly liking — not gustar. 'Me gusta' for people suggests attraction.
Ya caigo.
I get it now. / Now I see.
Caer for understanding — the penny dropping. '¡Ya caí!' is the moment of realisation.
¿Cuándo cae tu cumpleaños?
When is your birthday? (what day does it fall on?)
Dates 'fall' in Spanish. '¿En qué día cae?' = what day does it fall on? Used for days of the week.
Tricky bit
'Me cae bien' (I like him as a person — he makes a good impression) vs 'me gusta' (I'm attracted to him / I like it). Using 'me gusta' for a person you platонically like can accidentally imply attraction. 'Me cae bien' is the safe, friendly option.