How do I know whether to use Ser or Estar?

Ser and Estar are a common problem for beginners and more advanced learners alike. They both mean "to be", but are used for different things. Ser is used to... ...describe innate, fixed or "unchangeable" traits of people and objects (e.g. name, nationality, profession, colour, character traits, etc.) Example: Esta camiseta es azul. ...state time. Example: Son las cinco y media. Estar is used to... ...describe a changeable state (e.g. mood, physical state, etc.). Example: Después del trabajo, estoy muy cansada. ...state location. Example: La escuela está en el centro de la ciudad. These are the most common and basic uses of the two verbs, altough there are a couple more to be discovered at a later stage. It is also worth mentioning that certain adjectives can be used with both ser and estar, but would mean something different depending on which one is being used. Example: La comida está muy rica. = The food is very tasty. Juan es rico. = Juan is rich. It might be a good idea to make a list including these particular adjectives as you encounter more of them. That way you won't struggle with them in the future.