To insert or place something into a particular location or position. She put in the key and turned it to unlock the door.
To submit or present something, such as a request or application. He decided to put in an application for the new job opening.
To contribute or invest time, effort, or resources into something. They put in a lot of hours to complete the project on time.
To make an official statement or complaint. She put in a complaint about the noise to the building manager.
To install or set up equipment or a system. The technician came to put in the new software on our computers.