Amy mailed the letter.
The letter was mailed by Amy.
South Sydney Rabbitohs were beaten by Sydney Roosters.

Sydney Roosters beat South Sydney Rabbitohs.
The passive voice is used if you don't know who performed the action descried in the sentence.
For example:
"My keys are stolen!"
Correct.
Why use passive voice in the following headline:
"Young talent sought after by numerous agencies",
rather than,
"Numerous agencies seek after young talent"
The subject is "Young talent", who is more important.
Headlines place the most important information first.
“Young talent sought after… object”
→ The focus is on young talent (the key topic of the article).
“Numerous agencies seek after young talent”
→ The focus shifts to the agencies, which may be less important.
We were invited by our neighbours to attend their party.
Passive.
Once a week, John cleans the garage.
Once a week, the garage is cleaned by John.
It is believed that Manny is, in fact, a math genius.
I/we/they believe that Manny is, in fact, a math genius.
Active voice is used to emphasize the person that does the action.
Correct
The homework will be collected at 5 PM.
Focus is on the action, not the person doing it.
The painting was sold to someone who later donated it to the college.
Passive.
The product will leave you mesmerised!
You will be mesmerised by the product!
Close-up shots of characters' faces are used to reveal their emotions.
The director uses close-up shots of characters' faces to reveal their emotions.
The passive voice is used if you want to reveal who did the action.
Incorrect: It is used when you DON'T want to reveal who did the action, or if you don't KNOW.
Why say,
"My keys are stolen!" (passive voice)
Because you don't know who stole the keys, so it's stronger to say that than "Someone stole my keys!".
Peter is going to build a house in summer.
Active.
The director filmed the scene in the desert.
The scene was filmed in the desert by the director.
Countless victims had their money stolen from.
They had stolen money from countless victims.
The subject of a sentence is the doer of the action.
Incorrect:
Subject is the doer in active voice.
The boy ate the apple.
Subject is the receiver in passive voice.
The apple was eaten by the boy.
In sport commentary, would the commentator use active voice or passive voice more? Why?
Active voice->
"He has the ball! He moves past his opponents! He scores!"- When commentating on an athlete's performance, using active voice is better/stronger/more helpful.
She received the gift.
Active.
She WAS GIVEN the gift would be passive. Receive is an active word.
I think that technology have enormously improved many aspects of society, including health, economy and education.
It is thought that many aspects of society, including health, economy and education, have been enormously improved by technology.
When a dishonest politician tries to claim no responsibility, they'd say,
"Mistakes were made."
But when an honest politician comes clean, they'd say....
"I made mistakes."
Passive voice is common in formal situations (news, reports)
Correct.
The award was received by the director.
(Más formal que: “The director received the award.”)
Why use active voice in a letter to the editor?
Because it makes you sound more passionate about the issue you are writing about.
The quiet cat secretly snuck up on the still and dirty rat and killed it using its paws.
Active.