Passive Voice is a comprehensive and objective explanation of passive voice and it's use in writing.
A passive construction occurs when you make the object of an action into the subject of a sentence. That is, whoever or whatever is performing the action is not the grammatical subject of the sentence.
Actually, the article may be too objective. If you want to succeed in writing on the Internet, you may want to use the active voice and avoid the use of the passive voice altogether.

Even when writing on scientific topics, you can still use the active voice without resorting to writing in the first person.

The active voice is simply superior for communicating meaning.