Active Voice An agent (the doer of the sentence) is the subject of the verb and does something. There may or may not be an object (the thing done or person done to.)
Emilio escribe un libro en español. (Emilio is writing a book in Spanish.)
Hago un pastel con miel. (I am making a cake with honey.)
Mi madre cocinó la pizza en el horno. (My mom cooked the pizza in the oven.)
Los ingleses establecieron las colonias hace 200 años. (The English established the colonies 200 years ago.)
Passive Voice The passive voice indicates what happened to the object where the object is acted upon by an outside agent, which can be hidden or highlighted depending on the situation. You will only use transitive verbs (verbs that require a direct object). The formula ser + past participle (+ por + agente) or se + 3rd person is used to create the passive voice.
El libro fue escrito en español por mi profesor. (The book was written in Spanish by my professor.)
La pizza fue cocida en un horno por mi madre. (The pizza was cooked in an oven by my mother.)
Se establecieron las colonias hace 200 años. (The colonies were established 200 years ago.)
Se hizo este pastel con miel. (This cake was made with honey.)
The Passive Voice Definition: A sentence in which the subject of the main verb is also acted on by the verb is in the passive voice. We can also say that the verb is in the passive voice. A common use of the passive voice is to indicate what happened to the subject of the sentence without saying who or what carried out the action (although the actor can be indicated in a prepositional phrase). In English, the passive voice is formed by using a form of the verb "to be" followed by the past participle. It is the same in Spanish, where a form of ser is followed by the past participle. The past participle in such cases is modified if necessary to agree in number and gender with the subject of the sentence. Term in Spanish: La voz pasiva. Examples in Spanish: 1. Las computadoras fueron vendidas. Note that the subject of the sentence (computadoras) is also the object acted on. Knowing the difference between active and passive voice makes a big difference in how things are phrased. The passive voice is used much more often in Spanish than English.
Wider Scope
Avoiding the Passive (Using the Impersonal SE) Working like a true reflexive (i.e., it looks as if it means that the subject does the action to itself), with the verb agreeing with its grammatical subject.
Books are sold in the street. Se venden libros en la calle (looks like it means that books sell themselves, but it clearly isn't a true reflexive).
The president's bodyguards could be seen everywhere. Por todas partes se veían los guardaespaldas del presidente (could possibly mean that the bodyguards were seeing themselves or each other). (b) Impersonal: se acts as the subject of the verb, which is singular. This is not strictly correct, except when used as a way of avoiding the type of ambiguity shown above in the bodyguards example. The person who is the subject of the passive sentence in English can now be the direct object (marked with 'personal a').
Books are sold in the street. Se vende libros en la calle (not as acceptable as 'se venden').
The president's bodyguards could be seen everywhere. Por todas partes se veía a los guardaespaldas del presidente (removes the ambiguity).