The document presents an introduction to deep reinforcement learning, detailing the process of building agents that learn optimal policies within Markovian environments where the next state depends on the current state. It highlights the evolution of reinforcement learning since the 1980s, including its reliance on dynamic programming algorithms and the rise of deep learning techniques to handle complex environments. Various topics within deep reinforcement learning, such as multi-agent systems and policy-based methods, are also discussed, alongside recommended resources for further learning.