A key is a small tool usually made of metal. People use it to open or lock doors, boxes, or cars.
I have lost my house key.
She put the key in the door.
This meaning uses 'key' in a figurative way. It means an important thing that helps solve a problem or understand something.
Hard work is the key to success.
Trust is the key in a good friendship.
A key here means a guide or system used to understand signs or symbols. For example, in maps or music, it helps people read correctly.
The music key is C major.
The map has a key for the symbols.
This meaning means a button on a keyboard or instrument. When you press it, it makes a letter, number, or sound.
Press the space key to start.
The piano keys are black and white.
Here, 'key' means one of the buttons you press on a piano or computer keyboard to make a sound or write a letter.
He played fast on the piano keys.
She typed quickly on the computer key.
This verb means to press keys or buttons on a keyboard or machine to put in data or control it.
Please key in your password.
He keyed the numbers quickly.
In music, the key is the main note and scale around which a song or piece is made. It helps musicians play in the right tune.
The song is in the key of G major.
She sang the song in a high key.
