Self-healing materials research spans many academic disciplines and employs a wide range of methodologies. Some of the developed concepts are driven by the direct application of the materials. However, a deeper understanding of the basic mechanisms and principles of self-healing materials is still a challenging aim. Nature has mostly served as an inspiration for the development of new self-healing materials, and it will undoubtedly continue to be a significant source of inspiration for the creation of novel ideas. This review encompasses the principles of self-healing mechanisms based on the concepts of autonomous and non-autonomous procedures. Studies based on smart composite materials with autonomous self-healing properties are also included and discussed from two aspects of intrinsic or extrinsic abilities, taking into consideration their components and structures as well as the design of these composites. Finally, special attention is given to the application of the materials in several fields such as aerospace, automotive, marine, energy, medical and healthcare, military, and construction.