High-entropy alloys (HEAs) have attracted significant attention due to their unique microstructures and exceptional properties. This paper explores the relationship between the unique microstructures and behaviors of HEAs. HEAs are characterized by their high entropy, which represents disorder and randomness, and their structure, which is analogous to information. The arrangement of atoms in a material determines its properties, and HEAs offer diverse structural designs. Examples of HEA properties include high fracture strength with excellent ductility, antiballistic capability, exceptional radiation resistance, and corrosion resistance. The paper discusses various unique material structures and properties, emphasizing the intricate relationship between structure and performance. HEAs have expanded the composition space by using multiple elements and exploring compositions in and around the central regions of phase diagrams. Entropy is a metric for quantifying disorder in alloy structures. The entropy formula is given by $ S_i = R\sum x_i \ln(1/x_i) $, where $ x_i $ is the mol percent of a component. HEAs offer potential for forming diverse and innovative microstructures. Recent research has confirmed the feasibility of creating complex compositions within HEAs, leading to microstructures with adjustable stacking fault energies, dislocations that undergo jerky movements, nanotwins, and phase changes into martensite during plastic deformation. HEAs can be designed by considering various parameters associated with their constituent elements. The yield strength and atomic size difference ($ \delta $) have been studied, with HEAs situated in the region of low $ \delta $ values. Materials with face-centered cubic (FCC) structures generally exhibit lower yield strengths than other HEAs, while those with body-centered cubic (BCC) structures tend to have higher yield strengths and larger $ \delta $ values. HEAs have unique properties such as low tough-brittle transition temperature, resistance to irradiation and corrosion, and exceptional dimensional stability. These properties are due to the special atomic random lattice occupancy of HEAs. The paper introduces the types of special properties resulting from special structure design and compositions.High-entropy alloys (HEAs) have attracted significant attention due to their unique microstructures and exceptional properties. This paper explores the relationship between the unique microstructures and behaviors of HEAs. HEAs are characterized by their high entropy, which represents disorder and randomness, and their structure, which is analogous to information. The arrangement of atoms in a material determines its properties, and HEAs offer diverse structural designs. Examples of HEA properties include high fracture strength with excellent ductility, antiballistic capability, exceptional radiation resistance, and corrosion resistance. The paper discusses various unique material structures and properties, emphasizing the intricate relationship between structure and performance. HEAs have expanded the composition space by using multiple elements and exploring compositions in and around the central regions of phase diagrams. Entropy is a metric for quantifying disorder in alloy structures. The entropy formula is given by $ S_i = R\sum x_i \ln(1/x_i) $, where $ x_i $ is the mol percent of a component. HEAs offer potential for forming diverse and innovative microstructures. Recent research has confirmed the feasibility of creating complex compositions within HEAs, leading to microstructures with adjustable stacking fault energies, dislocations that undergo jerky movements, nanotwins, and phase changes into martensite during plastic deformation. HEAs can be designed by considering various parameters associated with their constituent elements. The yield strength and atomic size difference ($ \delta $) have been studied, with HEAs situated in the region of low $ \delta $ values. Materials with face-centered cubic (FCC) structures generally exhibit lower yield strengths than other HEAs, while those with body-centered cubic (BCC) structures tend to have higher yield strengths and larger $ \delta $ values. HEAs have unique properties such as low tough-brittle transition temperature, resistance to irradiation and corrosion, and exceptional dimensional stability. These properties are due to the special atomic random lattice occupancy of HEAs. The paper introduces the types of special properties resulting from special structure design and compositions.