The two verbs to be in Spanish:

The Spanish language has two verbs to be to express a quality or an attribute: estar and ser

1) the verb estar is used to express a contingent quality, some local, transient character:

Estoy en Madrid, I'm in Madrid
María está sentada en un café, María is sitting in a café
La puerta está cerrada, the door is closed
Mi hijo está enfermo, my son is ill
Estamos en primavera, we are in spring
Están escondidos, they are hidden

Conjugation of estar:

(you will find the conjugation of numerous verbs with the address: http://www.lapasserelle.com/conjugacion/ + verb + .html, so http://www.lapasserelle.com/conjugacion/estar.html gives the complete conjugation of estar)

2) the verb ser is used to express fundamental qualities, aspects that are unlikely to change:

Soy Inglés, I'm English
El Himalaya es muy alto, the Himalaya is very high
Pero la Sierra de Guadarrama no es muy alta, but the Sierra de Guadarrama is not very high
Es fácil, it's easy
La casa es verde, the house is green

Conjugation of ser:

 

3) Since the rule about the use of ser or estar is not without ambiguity or exception, it is good to memorize a few expressions:

- first of all those given above, which follow more or less the rule

- secundly, the following examples:

Mi hijo está enfermo,my son is ill
Pero es feliz porque no tiene que ir a la escuela, but he is happy because he doesn't have to go to school

La casa es verde, the house is green
La ciruela está verde, the plum is green (not yet ripe)