The Differences Between Ser and Estar Verb

A frequent question that comes to me is about the verbs ser and estar. Many students do not realize the use and the difference between the verb ser and estar because the most often translated as the verb be in English... there is one word in English for two in Portuguese, no wonder English speaking learners get confused!

But first, Just as a quick reminder about verb ser and estar conjugated in the Present Indicative tense as follows:

Eu sou | estou

Tu és | estás

Ele/ela é | está

Nós somos | estamos

Vos sois | estais

Eles/elas são | estão

The main idea is that ser is for intrinsic, somewhat permanent or long-term state and physical characteristics:

O meu nome é Ana. My name is (permanently/always) Ana.

O sol é amarelo. The sun is (permanently/always) yellow.

It gives a sense of permanency or habitual nature, when used with an adjective:

Eu sou alta. I am (permanently/always) tall.

We use the verb ser to attach a name to a profession or lifestyle:

Eu sou bióloga. I am Biologist.

Eu sou vegetariana. I am vegetarian.

The verb ser also expresses the hour, day, date, time.
 São oito e vinte minutos.  It's eight twenty.
É meia-noite. It's midnight
Hoje é dia 7 de janeiro. Today is January 7
Hoje é sábado. Todays is Saturday.

The verb ser is used to express the location of homes or places:

A livraria é ao lado da loja das fotocópias. The bookstore is next to the shop of the photocopies.

A casa-de-banho é ao fundo do corredor. The en-suite is down the hall.

Whereas estar is for temporary, passing things or changing state of being. 

Eu hoje estou inteligente. Today I look intelligent (at this time).

A cerveja está gelada. The beer is (temporarily) cold.

Because they are temporary, some adjectives are always used with the verb estar:

Eles estão cansados. They are (temporarily) tired. 

Eles estão contentes. They're happy.

Expresses the temporary location of people and / or objects.

O carro está perto do cinema. The car is near the cinema.

O Pedro está em casa da avó. Pedro is in grandma's house.

O gato está debaixo da mesa. The cat is under the table.

We used to talk or Express the atmospheric state.

Hoje estão 5 graus. Today is five degrees.

Está frio! It is cold!

Some more examples that may help to understand the difference between ser and estar:

Eu sou Portuguesa. I am (permanently/always) Portuguesa.

Ele é casado. He is (somewhat permanently) married.

A Susana está no ginásio. Susan is (temporarily) at the gym. 

Os bolos desta pastelaria geralmente são óptimos, mas hoje não estão muito bons. The cakes of this pastry are usually great, but today are not very good.

Notice that there are some cases where you could use both ser or estar but the meaning changes when we use one or the other case. 

Ela é bonita, ela está bonita.
She is not (permanently/always) beautiful, she is (temporarily) beautiful.

In the first case, we mean that the girl is naturally pretty (lucky girl). In the second case, mean that she is prettier than usual (maybe she dress nice clothes, got a new haircut, or otherwise accessorized herself, or makeup). We use the second case when we want to call attention to the fact that she is prettier due to some temporary condition.

Ele está doente. He is (temporarily disease) sick

Ele é doente. He is (permanently, like a cronic) sick.

Another example, in both cases translate to 'he is sick'. However, the first sentences says that he isn't usually sick, but is at the moment. The second case means that he is sick now, was in the past and will be in the future, for example a hereditary disease, or chronic diseases.

Eles são gordos. They are (permanently, if they born and still) fat.

Eles estão gordos. They are (temporarily, if they usually are thin) fat.

For the past and future, use the same rules:
Eu estive doente. I was sick.
Os bolos não eram bons. The cakes were not good.

The difference between the two is sometimes jokingly used by Portuguese and Brazilians:

Ela não está bonita, ela é bonita.
She is not (temporarily) beautiful, she is (permanently/always) beautiful.