Its difficult to give a single clear answer, because there are many exceptions to this rule. But, essentially, "estar" is used to express something temporary, or a state of being which exists at one particular moment in time, whether temporary or permanent. "Ser" is used to express permanent state of being, and to equate two distinct things or concepts (this = that). This is probably as clear as mud, so feel free to send me a message, and maybe we can discuss this more off-line.

Hi¡ "estar" (estoy) means that someone is physically doing something or being in an specific place (it's like presence).this verb is used to answer: where are you? And what are you doing? "ser" is for description, this verb is the answer of what are you?

A difficult question because in english "to be" is "Ser" and "Estar"... "Ser" is used to talk about the character, identity, or description of someone or something.. For example: "Soy alto" (I am tall) // "Soy loco" (I am crazy) // "Soy inteligente" (I am smart) "Estar" is used to talk about location, emotions, conditions of things, etc. For example: "Estoy en la cocina" (I am in the kitchen) // "Estoy feliz" (I am happy) // etc I think this is one of the most difficult things for english speakers, but it's all about practice!