"Fue" es el pretérito indefinido del verbo "ser", normalmente lo utilizamos para acciones que han finalizado y son puntuales. "Era" es el pretérito imperfecto de indicativo del verbo "ser", lo usamos para descripciones, estados y hábitos en el pasado. "Estaba" es el pretérito imperfecto de indicativo del verbo "estar" y tiene los mismos usos que hemos mencionado antes. Para saber cuando usamos "ser" y "estar" hay que estudiar un poco, porque sus usos no son muy intuitivos.

First you need to see the difference between ''ser'' and ''estar''. while both mean ''to be'' in english, they both are used in completely different contexts in Spanish. In short, ''ser'' is used to signify more permanent traits of any noun whereas "estar'' is used to denote temporary traits. e.g. ella está inferma : She is ill ella es inferma : She is a sick person See this website for more information: http://www.studyspanish.com/lessons/serest1.htm ***************************************************************************** Now on to fue and era. Both are past tenses of ser. So both mean ''was''. However, there can be two types of past tenses. In simple words, One is a DOT past and one is a LINE past. a DOT past is one in which a thing happens at a particular time in the past. a LINE past is when a thing continues to happen for some time. the DOT past uses the Preterite form of the verb : Fue the LINE past uses the Imperfect form of the verb : Era So you will say Cuando era niño, because you were a child for a long time rather than at a specific time See this link for more information: http://spanish.about.com/od/usingparticularverbs/a/era-fue.htm ********************************************************************************* Once you have understood that, the DOT past of estar is Estuve ( Something was at a particular time) the LINE past of estar is Estaba ( something was for a continuous period of time) ***************************************************************************************

it all boils down to this: To express location or a temporary state or condition, use the verb "estar " imperfect--estaba preterite--estuvo To express identity, or a quality or characteristic (rather than a temporary state), use the verb "ser" imperfect--era preterite--fue if you know how to use "imperfect" and "preterite" you'll get by. and this is an extensive subject it can't be explained briefly

Es un tema que a veces me confunde también.