SER
Real - Identification

Present Tense - I am, you are, etc.
soy           I am
eres          you (singular)(tú)
es             he, she, it (el, ella, Ud.)
somsos     we
son          you (pl.) they, those  (ellos, ellas, Uds.)

Ser denotes :
time,
age,
characteristics,
origin
possession,
location of event,
identity,
nationality,
as a linking verb (replaces subject)

Soy de Nueva York pero ahora, estoy en Dallas

Ël / Ella es de México pero ahora está en Dallas

ESTAR
General - Temporary

Present Tense -

Estar denotes:
temporary location of things and people,
condition today (meaning happy, ill, well, state if being at a certain time, results of actiion)
  e.g.,    Esto enfermo.
(I am ill but it is only a temporary condition.)

Estar is always used with contento, muerto o vivo.

Está - temporary
Es - permanent

El está borracho.  He is drunk. (temporary condition)
El es borracho.  He is a drunkard. (permanent condition)

Hester Chamberlain
Learning Assistance Center
Eastfield College