What is passive voice, and why are you told to avoid it?

There seems to be confusion between the actual grammar of active and passive voice, and prose that's accused of being "passive". So, let's start with the bare facts. When the action - the verb - of a sentence is being performed by the subject of the sentence, the sentence is in active voice. This kind of subject + verb + object construction is the basic building block of English. Anne chases the cat. The dog bit Ben. Here, the action is being done by the subject of the sentence: "Anne chases" and "The dog bit". When the action is being...