Previously, we looked at how to use the portuguese verb SER. Now let's look at the differences between SER and ESTAR.
Ser is for intrinsic, somewhat permanent characteristics.
My name is (permanently/always) Raquel.
I am (permanently/always) Brazilian.
He is (somewhat permanently) married.
Estar is for temporary passing things. (ESTAR - the definitive reference)
They are (temporarily) late.
Veronica is (temporarily) at the gym.
The difference between the two is sometimes jokingly used by Brazilians:
Joana: Wow! You are beautiful (at this moment)!
I am not (temporarily) beautiful, I am (permanently/always) beautiful.
Death. It seems like it might be a permanent situation (ahem) but not in portuguese. Use estar:
Ele está morto há muito tempo.
He's been dead a long time.
The day. Brazilians will say, "It's a beautiful day" and use both ser as well as estar. That's probably because if you just mean the weather, that's a temporary (estar) aspect, but you could also be saying that the day is beautiful intrinsically and will go down in history as such... !
O dia está bonito!
Hoje é lindo!