Which verb - SER or ESTAR? 2

Location — ser for events, estar for things/people — Location of people and moveable objects → estar: Está en la oficina. But events and fixed geographical features → ser: La conferencia es en el auditorio. Madrid está en España (location of a city uses estar in modern Spanish). This exception trips up many learners.

More adjectives with two meanings — Key pairs to know: ser rico (to be rich/wealthy) vs estar rico (to taste delicious). ser seguro (to be safe) vs estar seguro (to be sure/certain). ser vivo (to be sharp/clever) vs estar vivo (to be alive). In each case, ser gives a characteristic; estar gives a state.

Estar for unexpected or changed states — Estar can be used with adjectives that might normally go with ser to indicate a surprising or changed state: ¡Estás muy guapa hoy! (You look beautiful today — implying it's noticeably different from usual). This "affected estar" is nuanced and native-sounding; it implies change or impression rather than permanent description.