How many types of voices are there in English grammar?

Voice is that form of the verb (in a sentence) that shows whether or not the subject of the verb is the doer of the action denoted by the verb. A transitive verb (a verb that has an object) has two voices: Active and Passive. When the subject (in a sentence) of a verb also performs the action in the verb, the verb is said to be in the Active Voice. For example, Ravi(subject) writes a poem. When the subject (in a sentence) of the verb receives the action named in the verb, the verb is said to be in the Passive Voice. For example, A poem is written by Ravi(subject).