Cookie Clicker is a popular idle game where players click on a giant cookie to earn cookies. As players accumulate more cookies, they can use them to buy upgrades and power-ups that help them earn even more cookies without having to click as much. The game's mechanics are simple, but addictive, and it can be played for hours or even days on end as players aim to unlock all the upgrades and achievements. Cookie Clicker is known for its whimsical graphics and quirky sense of humor, and it has become a beloved classic in the idle game genre.