The transition from one-dimensional (1D) to two-dimensional (2D) quantum magnets, particularly in the context of spin-1/2 systems, has revealed surprising behaviors. The crossover between quasi-long-range order in 1D chains and true long-range order in 2D planes is not smooth. Ladders with an even number of legs exhibit purely short-range magnetic order and a finite energy gap to all magnetic excitations, while those with an odd number of legs display properties similar to single chains, including gapless spin excitations and power-law falloff of spin-spin correlations. Theoretical predictions of these novel ground states have been experimentally verified in various materials, such as vanadyl pyrophosphate (VO)2P2O7 and cuprates like SrCu2O3. These materials show exponential decay of spin susceptibility at low temperatures, indicating a spin gap. Neutron scattering and muon spin resonance (μSR) measurements support the presence of short-range spin order in 2-leg ladders, despite their unfrustrated nature. Theoretical studies have also explored the behavior of doped ladders, where holes can pair in a d-wave state, potentially leading to superconductivity. The doped 2-leg ladder system, La1-xSrxCuO2.5, shows metallic behavior and reduced resistivity upon doping, but no signs of superconductivity. However, the pairing of holes in a d-wave state and the presence of a large Fermi surface suggest a connection to the superconducting state of high-Tc cuprates. In conclusion, the study of low-dimensional quantum antiferromagnets, particularly ladders, has provided valuable insights into the rich physics of quantum systems and the complex behavior of materials with unique structural elements, such as high-Tc superconductors.The transition from one-dimensional (1D) to two-dimensional (2D) quantum magnets, particularly in the context of spin-1/2 systems, has revealed surprising behaviors. The crossover between quasi-long-range order in 1D chains and true long-range order in 2D planes is not smooth. Ladders with an even number of legs exhibit purely short-range magnetic order and a finite energy gap to all magnetic excitations, while those with an odd number of legs display properties similar to single chains, including gapless spin excitations and power-law falloff of spin-spin correlations. Theoretical predictions of these novel ground states have been experimentally verified in various materials, such as vanadyl pyrophosphate (VO)2P2O7 and cuprates like SrCu2O3. These materials show exponential decay of spin susceptibility at low temperatures, indicating a spin gap. Neutron scattering and muon spin resonance (μSR) measurements support the presence of short-range spin order in 2-leg ladders, despite their unfrustrated nature. Theoretical studies have also explored the behavior of doped ladders, where holes can pair in a d-wave state, potentially leading to superconductivity. The doped 2-leg ladder system, La1-xSrxCuO2.5, shows metallic behavior and reduced resistivity upon doping, but no signs of superconductivity. However, the pairing of holes in a d-wave state and the presence of a large Fermi surface suggest a connection to the superconducting state of high-Tc cuprates. In conclusion, the study of low-dimensional quantum antiferromagnets, particularly ladders, has provided valuable insights into the rich physics of quantum systems and the complex behavior of materials with unique structural elements, such as high-Tc superconductors.