This chapter delves into the mechanisms underlying self-healing materials, with a focus on both autonomous and non-autonomous healing processes. It provides an in-depth analysis of various self-healing strategies, including capsule-based systems, reversible covalent bonding, vascular healing networks, and extrinsic healing systems with embedded agents. The chapter also examines the role of environmental factors such as temperature, pressure, and external stimuli like light and electric fields, which influence healing efficiency. Key mechanisms are compared across parameters like activation methods, advantages, and limitations, offering insight into their practical applications. Additionally, challenges such as scalability, material compatibility, and healing efficiency are discussed, with potential solutions provided through hybrid approaches. The chapter concludes by exploring the future directions of self-healing materials, emphasizing the need for multi-functional, sustainable, and scalable systems.