What's the difference between 'Ser' and 'Estar'?

Both the verbs 'ser' and 'estar' can be translated to 'to be', however, they're used differently in Spanish. 

'Ser' is used to provide a definition or a description: Madrid es la capital de España = Madrid is the capital of Spain. Soy alto = I am tall. Ella es guapa = She is beautiful. 

'Estar' indicates a temporary circumstance (it explains how someone or something is now, at this very moment - it could change in the future) and locations: Estoy muy cansado = I am very tired. Josè està soltero = Josè is single. Barcelona està en el sur de España = Barcelona is in the south of Spain. Mi dormitorio està en el segundo piso = My room is on the second floor.