An AI agent is a software system that perceives inputs — messages, database changes, form submissions, or scheduled triggers — makes decisions based on defined logic or an AI model, and takes action without a human in the loop. Unlike a chatbot that only responds in conversation, an AI agent operates across your entire system: reading data, updating records, sending notifications, and routing work automatically. Modern AI agents are typically built on large language models like GPT-4o combined with workflow tools like n8n or Make.com and connected to your existing database.