AI agents are transforming the way industries operate by enabling automation, decision-making, and optimization across various domains. They possess the ability to learn, adapt, and function autonomously, unlike traditional software programs that rely on predefined instructions. AI agents can be classified into different types based on their level of intelligence and functionality, including simple reflex agents, model-based reflex agents, goal-based agents, utility-based agents, and learning agents. Each type is designed to handle specific tasks or environments, such as customer service chatbots, healthcare diagnostic systems, financial algorithmic trading, and robotics autonomous vehicles. To function efficiently, AI agents rely on a structured architecture comprising perception modules, decision-making modules, action modules, and learning modules. These components work together to enable AI agents to perceive their environment, make informed decisions, and execute actions effectively. However, AI agents also face several challenges and limitations, including context understanding and memory constraints, real-world adaptability, decision-making accuracy, privacy and security concerns, integration with existing systems, computational and energy costs, and human trust and reliability. Multi-agent systems (MAS) are another area of research, where multiple intelligent agents work together to achieve a shared goal or perform complex tasks. MAS can be cooperative, competitive, or hybrid, each functioning differently in various applications. When choosing an AI agent framework, developers must consider scalability, flexibility, customization, integration capabilities, ease of use and documentation, security, and compliance. Various open-source frameworks are available for building AI agents, including Langraph, CrewAI, AutoGen, Pydantic AI, and MonsterAPI. These frameworks provide the necessary tools for building, deploying, and managing AI agents effectively. The future of AI agents lies in their ability to learn, adapt, and collaborate, unlocking new efficiencies across industries. However, addressing security, ethical concerns, and system reliability remains crucial for responsible deployment.