Ser And Estar

There are two verbs "to be" in Spanish. SER and ESTAR.

ESTAR is mainly used to describe circunstancial states such a feelings, or phisical states:

ej: Estoy triste hoy (Today you are sad but tomorrow you may be happy)

Estoy enfermo (Today you are ill but next week you may feel better)

SER is used to descrive more stable situations. Things that will never change such as nationalities, professions...

ej: Soy espa ola (I will always be Spanish even if I change my nationality)

Soy m dico ( I will always be a doctor. I may change my career but once I get my degree it means I am a doctor)-