Active Voice:

Active voice is a grammatical voice common in many of the world's languages. It is the unmarked voice for clauses featuring a transitive verb in nominative–accusative languages, including English and most other Indo-European languages.
Active voice is used in a clause whose subject expresses the agent of the main verb. That is, the subject does the action designated by the verb. A sentence whose agent is marked as grammatical subject is called an active sentence. In contrast, a sentence in which the subject has the role of patient or theme is called a passive sentence, and its verb is expressed in passive voice. Many languages have both an active and a passive voice; this allows for greater flexibility in sentence construction, as either the semantic agent or patient may take the syntactic role of subject.

Examples

In the following examples the active and passive voice are illustrated with pairs of sentences using the same transitive verb.

Language	Active voice	Passive voice
English	The hunter saw the deer.	The deer was seen by the hunter.
French	Brackett a écrit ce livre.　(Brackett wrote this book.)	Ce livre a été écrit par Brackett. (This book was written by Brackett.)
Japanese	犬がかんだ。 (A dog bit [someone].)	犬にかまれた。　(By a dog [I] was bitten.)
German	Der Hund biss den Postboten.　(The dog bit the postman.)	Der Postbote wurde vom Hund gebissen. (The postman was bitten by the dog.)