This review discusses three transport regimes in semiconductor nanostructures: Coulomb blockade, diffusive and quasi-ballistic transport, and adiabatic transport. These regimes are characterized by different behaviors of electrons in artificial potential landscapes. The first regime, Coulomb blockade, involves quantum interference effects in disordered conductors. The second regime, diffusive and quasi-ballistic transport, is typical of disordered metals and is influenced by quantum interference as the dimensionality of the conductor decreases. The third regime, adiabatic transport, is characterized by macroscopic behavior in samples as large as 0.25 mm. Semiconductor nanostructures offer the unique possibility of studying quantum transport in an artificial potential landscape. This regime, known as ballistic transport, allows for the tailoring of transport properties by varying the geometry of the conductor. The physics of this regime is referred to as electron optics in the solid state. The Landauer formula, which relates conduction and transmission, has been instrumental in understanding quantum point contacts and their quantized conductance. In two-dimensional systems under a perpendicular magnetic field, the quantized Hall resistance is a key property. The magnetic length plays a role similar to the wavelength in the quantum Hall effect. The potential landscape in a 2DEG can be adjusted to suppress inter-Landau level scattering, leading to adiabatic transport. In this regime, macroscopic behavior may not be found even in large samples. The review covers the electronic properties of 2DEG in Si inversion layers and GaAs-AlGaAs heterostructures. The electronic properties of these systems are studied using various techniques, including transport measurements in the plane of the 2DEG. The density of states in two, one, and zero dimensions is discussed, along with the effects of magnetic fields on transport properties. The review also discusses the density of states in two, one, and zero dimensions, the Drude conductivity, Einstein relation, and Landauer formula. These concepts are essential for understanding the transport properties of semiconductor nanostructures. The review highlights the importance of these concepts in understanding the behavior of electrons in different transport regimes. The review concludes with a discussion of magnetotransport in semiconductor nanostructures. The effects of magnetic fields on transport properties are discussed, including the Hall effect and the quantized Hall resistance. The review emphasizes the importance of understanding these effects in the context of quantum transport in semiconductor nanostructures.This review discusses three transport regimes in semiconductor nanostructures: Coulomb blockade, diffusive and quasi-ballistic transport, and adiabatic transport. These regimes are characterized by different behaviors of electrons in artificial potential landscapes. The first regime, Coulomb blockade, involves quantum interference effects in disordered conductors. The second regime, diffusive and quasi-ballistic transport, is typical of disordered metals and is influenced by quantum interference as the dimensionality of the conductor decreases. The third regime, adiabatic transport, is characterized by macroscopic behavior in samples as large as 0.25 mm. Semiconductor nanostructures offer the unique possibility of studying quantum transport in an artificial potential landscape. This regime, known as ballistic transport, allows for the tailoring of transport properties by varying the geometry of the conductor. The physics of this regime is referred to as electron optics in the solid state. The Landauer formula, which relates conduction and transmission, has been instrumental in understanding quantum point contacts and their quantized conductance. In two-dimensional systems under a perpendicular magnetic field, the quantized Hall resistance is a key property. The magnetic length plays a role similar to the wavelength in the quantum Hall effect. The potential landscape in a 2DEG can be adjusted to suppress inter-Landau level scattering, leading to adiabatic transport. In this regime, macroscopic behavior may not be found even in large samples. The review covers the electronic properties of 2DEG in Si inversion layers and GaAs-AlGaAs heterostructures. The electronic properties of these systems are studied using various techniques, including transport measurements in the plane of the 2DEG. The density of states in two, one, and zero dimensions is discussed, along with the effects of magnetic fields on transport properties. The review also discusses the density of states in two, one, and zero dimensions, the Drude conductivity, Einstein relation, and Landauer formula. These concepts are essential for understanding the transport properties of semiconductor nanostructures. The review highlights the importance of these concepts in understanding the behavior of electrons in different transport regimes. The review concludes with a discussion of magnetotransport in semiconductor nanostructures. The effects of magnetic fields on transport properties are discussed, including the Hall effect and the quantized Hall resistance. The review emphasizes the importance of understanding these effects in the context of quantum transport in semiconductor nanostructures.