SER vs ESTAR: How, When and Why to use TO BE
http://www.youtube.com/watch?v=1r59lFAw180&feature=youtube_gdata_player



Routledge Frequency dictionary (p. 107)
Adjectives with ser/estar

All with "ser":
unico, importante, posible, general, anterior, capaz, comun, contrario, real, enorme, nacional, conocido, suficiente, absoluto, rapido, popular, famoso, preciso, amplio

All with "estar"
dispuesto, sentado, convencido, acostumbrado, contento, preocupado, satisfecho, compuesto, previsto. cansado, parado, prhibido, resuelto, escondido, dormido, agotado, ligado, vinculado, disponible

Vary:
Less than 50% of time with estar
rojo, firme, viejo, libre, activo, compleeto, vivo, sano, ciego, frio, aburrido, oscuro

Over 50% (but not much over) of time with estar
fijo, triste, limpio, claro, limitado, seco, definido


SER

Ser is used to classify and identify permanent or lasting attributes. If this general rule is too vague for you, think of the acronym D.O.T. Ser is used for Descriptions of a person or thing, Origins of a person or thing, and Time.

1. DESCRIPTION

For description, think of what you would say if someone asked you “How would you describe?” These are the essential qualities that define a person or thing and probably won’t change any time soon. These descriptions can be names, physical descriptions, personality or characteristic descriptions, occupations, religions, and even relationships to other people

Yo soy Raúl. (I am Raúl.)
Yo soy alta, morena, y delgada. (I am tall, dark-skinned, and thin.)
Amalia es inteligente, atrevida, y amable. (Amalia is intelligente, daring, and friendly.)
Soy profesora de español. (I am a Spanish teacher.)
Andrés es católico. (Andrés is Catholic.)
Lynne es mi madre. (Lynne is my mother.)

Descriptions with Ser

Ser is used for all permanent/long-term and personal descriptions. You would use ser to answer the question, “How would you describe ?”. Ser is used with the essential qualities that define a person or thing and that are not likely to change in the near future. These can be:
physical descriptions

Soy alta y delgada. - I am tall and thin.
Silvia es pelirroja y baja. - Silvia is red-headed and short.

*names

Soy Raúl. - I am Raúl.
Son Adela y Amalia. - They are Adela and Amalia.

*the job a person has

Soy profesora de español. - I am a Spanish teacher.
Son jardineros. - They are gardeners.

*the relationship a person has with someone else

Anita es mi hermana. - Anita is my sister.
Aaron es su prometido. - Aaron is her fiancé.

*a person’s religion

Andrés es católico. - Andres is Catholic.
Mis padres son budistas. - My parents are Buddhists.

2. ORIGIN

The place a person is from or the material something is made from is an origin. The origin of someone or something is not going to change when we use ser.

Celia es de España. (Celia is from Spain.)
Las sillas son de madera. (The chairs are made of wood.)

Ser is used to describe the place a person is from or the material something is made from. You would use ser to answer the question “Where/What is this from?”. Ser is used to describe the essential qualities of a person or thing and where it is from or what it is made is certainly essential to its description.

Origin of Place

Where a person or thing is from. This can be where a person was born or raised and also where an item was made. To describe a person’s home country or location, use a conjugated form of the verb Ser + de + location.

Celia es de España. (Celia is from Spain.)
Paralee es de Georgia. (Paralee is from Georgia.)
Estos quesos son de Francia. (Those cheeses are from France.)
Su vestido es de Italia. (Her dress is from Italy.)

Origin of Material

What an item is made from also uses Ser and is formatted in a similar manner to that used to describe a noun’s place of origin: a conjugated form of the verb Ser + de + material.

Las sillas son de madera. (The chairs are made from wood.)
Mi anillo es de oro. (My ring is made from gold.)

3. TIME

Time includes days, dates, and hours. For hours, use es for one o´clock and son for all other hours.

Hoy es miércoles. (Today is Wednesday.)
Ayer fue mi cumpleaños. (Yesterday was my birthday.)
Ahora es la una y media. (Right now it is one thirty.)

Using Ser with Time

Time can be days, dates, and hours.

Hoy es miércoles. (Today is Wednesday.)
Ayer fue mi cumpleaños. (Yesterday was my birthday.)
Ahora es la una y media. (Right now, it is one thirty.)
Eran las dos. (It was two o’clock.)

You only need to be able to count to 29 to be able to tell time in Spanish. When The time is less than 30 minutes, you state the time as you would in English using the formula Ser + la(s) + hour + y + minutes. Use es + la for times starting with one o’clock and son + las for all other hours.

Es la una y veinte. (It is one twenty.)
Son las tres y diez. (It is three ten.)
Son las nueve y veintinueve. (It is nine twenty nine.)
Son las diez y media. (It is ten thirty.)

To indicate the half hour in Spanish, use the word media, meaning half.

Once the clock ticks past 29 minutes, it is common to say how many minutes remain to the next hour. To do this, indicate the upcoming hour and the remaining minutes using the formula Ser + la(s) + hour + menos + minutes.

Son las diez menos veinte. (It is twenty minutes til ten./It is nine fourty.)
Es la una menos quince. (It is fifteen minutes til one./It is twelve fourty-five.)
Son las ocho menos cinco. (It is five minutes til eight./It is seven fifty-five.)

There are several time-related expressions that are commonly used in place of some numbers.

Es la una y cuarto. (It is one fifteen./It is a quarter after one.)
Son las cuatro y diez en punto. (It is four ten exactly.)
Son las nueve más o menos. (It is about nine o’clock.)
Salimos a las cinco. (We are leaving at five o’clock.)

Other useful time-related phrases:

Buenos días - Good morning
Buenas tardes - Good afternoon
Buenas noches - Good evening
¿Qué hora es? - What time is it?
¿Cuándo…? - When…?

A note on expressions of the state of affairs.

Some phrases that seem to deal with time will use the verb estar as they are indicating a state of where something stands.

¿A qué día estamos? - What day is it? (Literally: What day are we at)?
¿A cuántos estamos del mes? - What day of the month is it? (Literally: At which (day) are we up to in the month?)
Estamos a sábado. - Today is Saturday (Literally: We are at Saturday).

In such expressions the emphasis is on the state of affairs, similar (though not quite the same) as such expressions as, “How are we looking on time?” or “How are we doing for time?” A decent analogy can be drawn by considering the etymology of the word estar which shares the same root as the English verb “to stand.” Looking at it this way, one might reasonably assume that such expressions are similar to “Where do we stand for time?” or “How are we standing on time?” where the focus is more on a condition than telling an actual time.







ESTAR

Estar is used to indicate temporary states and locations. If the general rule doesn’t suffice, think of the acronym LoCo. Estar is used for Locations and Conditions.

1. LOCATIONS

These can be a physical position or posture or simply where something is (temporarily, permanently, or even conceptually).

Mi abuela está sentada. (My grandmother is sitting down/seated.)
El baño está a la derecha de la sala. (The bathroom is to the right of the living room.)
Estamos en el café ahora y estaremos en el cine en 20 minutos. (We are at the café right now and we will be at the movie theatre in 20 minutes.)
Mi abuelo está en la luna. (My grandfather is out of it/lost.)

Estar is used to express a person or item’s geographic or physical location. These can be permanent or temporary, real or imaginary.

El baño está a la derecha de la sala. (The bathroom is to the right of the living room.)
Estamos en el café ahora y estaremos en el cine en 20 minutos. (We are at the café right now and we will be at the movie theatre in 20 minutes.)
¿Dónde está España en el mapa? (Where is Spain on the map?)
Mi abuelo está en la luna. (My grandfather is out of it/lost/on the moon.)

A person or things position or posture is also included in location.

Mi abuela está sentada. (My grandmother is sitting down/seated.)
Yo estaba acostada cuando me llamaste. (I was lying down when you called me.)

*Exception! The location of an event or party is described using Ser, not Estar.

La fiesta es en mi casa. (The party is at my house.)
Su boda es en una viña. (Their wedding is at a vineyard.)

2. CONDITIONS

These can be physical, mental, or emotional states. Things that are likely to vary over several hours, days, or even years can be conditions.

Estoy tan cansada esta mañana. (I am so tired this morning.)
Mis niños están enfermos hoy. (My children are sick today.)
Mi padre está un poco loco. (My father is (acting) a little crazy.)
Estoy triste. (I am sad.)
Ella está contenta porque recibió unas flores de su novio. (She is happy because she received some flowers from her boyfriend.)

Estar is used to express a person’s condition. A good way to think of this is how the person feels. A condition can be:

*An emotion

Estoy triste. (I am sad.)
Ella está contenta porque recibió unas flores de su novio. (She is happy because she received some flowers from her boyfriend.)

*A temporary physical state

Estoy cansada esta mañana. (I am tired this morning.)
Mis niños están enfermos hoy. (My children are sick today.)

*A temporary mental state

Mi padre está un poco loco. (My father is (acting) a little crazy.)
Los estudiantes están muy confundidos. (The students are very confused.)

A helpful tip for remembering conditions is to ask, “Can I feel _?” If the answer is yes, use estar. If instead the adjective is better stated “I am __.” then you may want to use ser.

Triste (Sad)

Can I feel sad? Yes! Use estar.
Estoy triste.

Morena (Brunette)

Can I feel brunette? No. Am I brunette? Yes! Use ser.
Soy morena.