Simple Definition:

A CEO, or Chief Executive Officer, is the highest-ranking person in a company who is responsible for making major decisions and managing the overall operations [the day-to-day activities] of the organization.

Examples:

• The CEO of Apple Inc. is Tim Cook, who oversees the development and launch of new products.
• A startup company might have a CEO who is also responsible for fundraising, hiring, and marketing.

Very Simple Definition:

A CEO is the boss of a company who makes the big decisions and runs things.

Examples:

• The CEO is like the captain of a team, telling everyone what to do and making sure everything runs smoothly.
• The CEO is the person who decides how much money employees get paid and whether or not to expand the company.