Ser vs Estar

Ser and estar can both be translated as "to be."

Notice that the sentence below can have two different meanings in English.

The soldier is green.

- The soldier has never experienced combat.

- The soldier is the color green. (plastic toy soldier)

In the first case, our example speaks of the condition of the soldier. The soldier is green because he has never experienced combat. When the condition of the soldier changes, that is, after he has experienced combat, he will no longer be green.

In the second case, our example speaks of the essential characteristics of the soldier. The toy soldier is green in color.

In English, the verb "to be" can be used to tell how something is (the condition) and what something is (the essence).

What is the status of the soldier?

He is inexperienced.

What color is the (toy) soldier?

He is green.

In Spanish, a different verb is used to express "to be" depending on whether the speaker intends to address a condition or an essential quality.

El Soldado está verde.
The soldier is green. (condition)

El Soldado es verde.
The soldier is green. (essence)

Note how the adjective "verde" actually changes meaning, depending upon whether it is used with ser or estar.

El Soldado está verde.
(condition: verde = inexperienced)

El Soldado es verde.
(essential characteristic: verde = the color green)

To address condition, use estar. To address an essential quality, use ser. If you are talking about what something is, use ser; if you are talking about how something is, use estar.

Examples:

What is she like? She is quiet.
Use ser:
Ella es callada.

How is she acting? She is being quiet.
Use estar:
Ella está callada.