Active Voice is usually preferred.
Passive Voice - the subject receives the action and it might have the phrase "by the...".
Passive Voice is usually avoided except in 2 cases: 1. Subject of the sentence is indefinite/general. E.g. Rice is not grown in these fields (good). They do not grow rice in these fields (poor) 2. Depends on what the writer emphasises. E.g. America was discovered by Columbus. or Columbus discovered America.