Estar and ser - spanish

Soy = permanent quality. Soy de Inglaterra, soy simpático, soy grande. Estoy = temporary quality. Estoy en Inglaterra, estoy triste, and so on. Note that if you said "estoy grande" it would probably mean that you were only tall for that moment, because you were wearing big shoes or whatever, and if you said "soy triste" it would probably mean you were a generally sad person - i.e. you were always sad. Both are (obviously) generally not used though.

That makes a lot of sense. Thanks

Sometimes I find it hard though to know when to use either one, as the sentence can be very ambigious at times. For example:

"She is happy" - this is a very ambigous sentence as it could mean that she is always happy, or she is just feeling happy. That is when it gets quite confusing.

Thanks again.