An agent is something that acts, interacts, and reacts. It is not an abstract concept but an actual instance—a real and functioning entity. An agent plays a role in the world, carrying out actions, engaging with other entities, and responding to changes. This dynamic nature is what distinguishes an agent from other forms of systems or ideas.

Agents are characterized by having a local state, which means they maintain their own specific conditions. This state allows them to operate independently and adapt to their context. For example, a program running on a computer might have its own setup and configurations, while a person may act based on their own understanding of a situation. This local state is crucial for how agents interact with the environment and make decisions.

In addition to their state, agents rely on data and knowledge to function effectively. They gather and store information, using it to guide their actions and interactions. A navigation app, for instance, uses map data to help users find directions, while a human draws on their experience and knowledge to solve problems or adapt to challenges. Data and knowledge are the foundation of an agent’s ability to act with purpose.

Agents can take many forms. They might be programs performing tasks, humans acting with intent, apps that assist users, or even companies operating collectively to achieve goals. For example, a company delivering products or services can be seen as an agent—working as a unit with state, data, and the ability to act, interact, and react. Ultimately, anything that operates autonomously or semi-autonomously within a system can be considered an agent.

Understanding what an agent is helps us appreciate its role in practical systems. Whether it’s software performing tasks, a person making decisions, or an organization navigating complex goals, agents are all around us. They are essential entities that shape how actions are carried out, interactions occur, and reactions drive progress.