Ser vs. estar

Spanish has two verbs that mean "to be": ser and estar.

Use ser for identity and traits

Use ser to talk about what someone or something is. This includes essential characteristics, personality traits, and physical descriptions.

They are nice and happy.
Ellas son simpáticas y felices.

Use estar for states and conditions

Use estar to talk about how someone feels, where something is located, or temporary conditions (like being open, closed, clean, or dirty).

The girl is angry at school.
La niña está enojada en la escuela.
The office table is clean.
La mesa de la oficina está limpia.

Seeing them together

It is common to use both verbs in the same sentence to contrast a permanent trait with a temporary condition.

The car is new, but it is dirty.
El carro es nuevo, pero está sucio.
The grandfather is nice, but now he is angry.
El abuelo es simpático, pero ahora está enojado.

Some adjectives change their meaning depending on which verb you use. For example, aburrido means "boring" with ser, but "bored" with estar.

boring / bored
aburrido
The book is boring and long.
El libro es aburrido y largo.
The professor is boring, but the students are not bored.
El profesor es aburrido, pero los estudiantes no están aburridos.