Tough hydrogels are promising materials for load-bearing applications due to their ability to resist multiple cycles of extreme mechanical impact. This review aims to clarify the mechanical properties of state-of-the-art tough hydrogels by providing a comprehensive library of fracture and mechanical property data. Common methods for mechanical characterization of high-performance hydrogels are introduced, followed by various modes of energy dissipation used to obtain tough hydrogels. These modes help categorize datasets and assess the material's mechanical properties. Current applications are considered, and tough hydrogels are compared with existing materials, highlighting promising future opportunities. Tough hydrogels are cross-linked, water-based polymer networks with tunable properties such as elasticity, toughness, and flexibility. The global market for hydrogels is projected to grow significantly, with applications in tissue engineering, drug delivery, and soft robotics. Mechanical characterization of tough hydrogels involves tensile tests, where a dumbbell-shaped specimen is clamped and stretched to measure properties like elastic modulus, yield strength, and toughness. Fracture toughness is crucial for load-bearing applications, as it measures a material's resistance to crack propagation. Energy dissipation in tough hydrogels is achieved through sacrificial bonds, such as double networks or non-covalent interactions. These mechanisms allow the hydrogel to reversibly recover from mechanical impacts. Metal–ligand interactions, ionic interactions, hydrogen bonding, and microphase separation are key energy dissipation modes. Composite materials with nanofillers and self-assembled structures also contribute to tough hydrogels. The mechanical properties of tough hydrogels are influenced by factors such as water content, which affects their stiffness and fracture toughness. Double network hydrogels, for example, combine covalent and physical cross-links to enhance mechanical properties. Studies show that increasing the water content can reduce stiffness but improve fracture energy. The fracture energy (Γ) and elastic modulus (E) are critical parameters, with higher values indicating better performance under mechanical stress. Tough hydrogels have been developed using various strategies, including metal coordination, ionic interactions, and self-assembly. These materials exhibit high stretchability and energy dissipation capabilities, making them suitable for applications such as biomedical devices and flexible electronics. The review highlights the importance of understanding the structure–property relationship in hydrogels to engineer materials with desired mechanical properties. Future research should focus on optimizing these properties for new applications and improving the performance of existing materials.Tough hydrogels are promising materials for load-bearing applications due to their ability to resist multiple cycles of extreme mechanical impact. This review aims to clarify the mechanical properties of state-of-the-art tough hydrogels by providing a comprehensive library of fracture and mechanical property data. Common methods for mechanical characterization of high-performance hydrogels are introduced, followed by various modes of energy dissipation used to obtain tough hydrogels. These modes help categorize datasets and assess the material's mechanical properties. Current applications are considered, and tough hydrogels are compared with existing materials, highlighting promising future opportunities. Tough hydrogels are cross-linked, water-based polymer networks with tunable properties such as elasticity, toughness, and flexibility. The global market for hydrogels is projected to grow significantly, with applications in tissue engineering, drug delivery, and soft robotics. Mechanical characterization of tough hydrogels involves tensile tests, where a dumbbell-shaped specimen is clamped and stretched to measure properties like elastic modulus, yield strength, and toughness. Fracture toughness is crucial for load-bearing applications, as it measures a material's resistance to crack propagation. Energy dissipation in tough hydrogels is achieved through sacrificial bonds, such as double networks or non-covalent interactions. These mechanisms allow the hydrogel to reversibly recover from mechanical impacts. Metal–ligand interactions, ionic interactions, hydrogen bonding, and microphase separation are key energy dissipation modes. Composite materials with nanofillers and self-assembled structures also contribute to tough hydrogels. The mechanical properties of tough hydrogels are influenced by factors such as water content, which affects their stiffness and fracture toughness. Double network hydrogels, for example, combine covalent and physical cross-links to enhance mechanical properties. Studies show that increasing the water content can reduce stiffness but improve fracture energy. The fracture energy (Γ) and elastic modulus (E) are critical parameters, with higher values indicating better performance under mechanical stress. Tough hydrogels have been developed using various strategies, including metal coordination, ionic interactions, and self-assembly. These materials exhibit high stretchability and energy dissipation capabilities, making them suitable for applications such as biomedical devices and flexible electronics. The review highlights the importance of understanding the structure–property relationship in hydrogels to engineer materials with desired mechanical properties. Future research should focus on optimizing these properties for new applications and improving the performance of existing materials.