What is clock in? How to use in English

The phrase "clock in" originated in the early 20th century in the context of factory work. It comes from the use of time clocks, also known as punch clocks, which were installed in factories to keep track of employee hours. Employees would "clock in" by inserting atime card into a mechanical device that stamped it with the time, signifying the beginning of their shift. This process was called "clocking in" because the time was recorded by the clock. When an employee finished their shift, they would "clock out" and the card would be punched again, registering the end of their workday. The phrase "clock in" quickly became a part of everyday language as it was convenient way to describe the act of starting work at this time. Now, the expression is used more broadly to refer to starting any job or task at a designated time, regardless of whether a time clock is involved.