Officers actively operate and manage the business.
A company can have several different officer positions. Every company must have a President and Secretary (which can be the same person). Companies can create other positions like CEO, Vice-President, and Treasurer. These can all be held by the same person.
Officers are appointed by the directors to run the day-to-day operations of the corporation.
Officers owe a duty of care to the corporation. This means they must act honestly and in the best interests of the corporation. They must also avoid conflicts of interest.