The thermally-induced shape-memory effect (SME) in shape-memory polymers (SMPs) allows materials to change shape in response to heat, recovering their original form upon heating. This effect is driven by the entropy-driven recovery of a mechanical deformation, which is temporarily fixed by physical crosslinks. SMPs have significant technological importance in various applications, including packaging, textiles, and biomedical devices. Recent research focuses on developing multifunctional SMPs, combining SME with additional functions such as drug release, electrical conductivity, and degradability. Multifunctional SMPs can be created through various architectures, including covalent polymer networks, thermoplastic (multi)block copolymers, and multimaterial systems. These systems enable the integration of multiple functions, such as hydrolytic degradability, by incorporating functional groups or additional materials. The performance of SMPs is influenced by their thermal transitions, which determine the switching temperature (T_sw) and the recovery properties. The SME is quantified by shape fixity ratio (R_f) and shape recovery ratio (R_r), which measure the material's ability to fix and recover its shape. The thermally-induced SME can be triggered by heat, light, or other stimuli, and the ability to respond to external stimuli without direct contact is crucial for applications like intelligent implants. The properties of SMPs, such as permeability, transparency, elastic properties, and dielectric behavior, change during SME. For example, permeability can be controlled by adjusting the switching temperature, while transparency changes as the material transitions between crystalline and amorphous states. Elastic properties are influenced by the flexibility of the polymer chains, and dielectric properties depend on the alignment of dipoles within the polymer matrix. Multifunctional SMPs are essential for advanced applications, requiring the integration of multiple functions into a single material. The development of such materials presents significant challenges and opportunities for fundamental research, with potential applications in biomedical, aerospace, and smart textiles. The future of SMPs lies in the integration of multifunctionality with emerging technologies, such as light-sensitive SMPs and reversible shape-changing effects.The thermally-induced shape-memory effect (SME) in shape-memory polymers (SMPs) allows materials to change shape in response to heat, recovering their original form upon heating. This effect is driven by the entropy-driven recovery of a mechanical deformation, which is temporarily fixed by physical crosslinks. SMPs have significant technological importance in various applications, including packaging, textiles, and biomedical devices. Recent research focuses on developing multifunctional SMPs, combining SME with additional functions such as drug release, electrical conductivity, and degradability. Multifunctional SMPs can be created through various architectures, including covalent polymer networks, thermoplastic (multi)block copolymers, and multimaterial systems. These systems enable the integration of multiple functions, such as hydrolytic degradability, by incorporating functional groups or additional materials. The performance of SMPs is influenced by their thermal transitions, which determine the switching temperature (T_sw) and the recovery properties. The SME is quantified by shape fixity ratio (R_f) and shape recovery ratio (R_r), which measure the material's ability to fix and recover its shape. The thermally-induced SME can be triggered by heat, light, or other stimuli, and the ability to respond to external stimuli without direct contact is crucial for applications like intelligent implants. The properties of SMPs, such as permeability, transparency, elastic properties, and dielectric behavior, change during SME. For example, permeability can be controlled by adjusting the switching temperature, while transparency changes as the material transitions between crystalline and amorphous states. Elastic properties are influenced by the flexibility of the polymer chains, and dielectric properties depend on the alignment of dipoles within the polymer matrix. Multifunctional SMPs are essential for advanced applications, requiring the integration of multiple functions into a single material. The development of such materials presents significant challenges and opportunities for fundamental research, with potential applications in biomedical, aerospace, and smart textiles. The future of SMPs lies in the integration of multifunctionality with emerging technologies, such as light-sensitive SMPs and reversible shape-changing effects.