The combination of smart materials to print a three-dimensional (3D) product has primarily driven the development of innovative technology, or four-dimensional (4D) printing. 3D-printing technology seems to have provided extensive enhancement with materials, printers, and processes in the past decade. The additive manufacturing (AM) industry is discovering the latest applications, materials, and 3D printers. AM can be defined as a method of formulating 3D parts through compiling the material layer by layer, which is conventionally made of plastics, metals, or ceramics; nevertheless, “smart” materials are also being used these days. These smart materials can be adjusted with printable characteristics or structures when additional stimulants are implemented. These 3D-printed materials modify their shape or properties with time, which is the fourth dimension and can merge with conventional 3D printing. 4D printing is the system whereby a 3D-printed object changes itself into a different structure as the result of the impact of environmental stimuli such as temperature, light, or other factors. 4D printing will open new possibilities that are convenient in significant applications, will work in extreme surroundings, and will help create a transformable structure. The objective of this review is to examine and assess the reputation and development of 4D-printing technology, including the 4D-printing process, materials, and potential applications. This review determines that 4D-printing technology has potential applications in various fields, but more research work will be essential for prospective accomplishments of this technology.