When do you use 'ser' and when do you use 'estar' in Spanish?

This is something almost all English speakers learning Spanish struggle with, particularly since all the rules seem to have exceptions!Generally speaking, you use 'ser' for characteristics (descriptions, occupations, origin), which are usually, although not always, permanent, and 'estar' for states (conditions, locations, feelings), which are usually, although not always, temporary. You also use 'ser' for time and for the location of parties!e.g. Ella es alta. (description) Yo soy estudiante. (occupation) Ellos son de Espana. (origin) La fiesta es en mi casa. (event) Ella está cansada (condition) Yo estoy contenta. (feeling) La catedral está allí. (location)