Gauge-mediated supersymmetry breaking is an alternative to gravity-induced supersymmetry breaking, offering a natural suppression of flavour violations and distinctive phenomenological features. This review discusses the structure, experimental implications, and models of gauge-mediated supersymmetry breaking, emphasizing their ability to generate soft terms without introducing large flavour violations. The theory involves a secluded sector for supersymmetry breaking and a messenger sector that communicates this breaking to the observable sector via gauge interactions. The messenger sector introduces a scale M, which is unrelated to the flavour scale Λ_F, allowing for a natural decoupling of flavour violations. The soft terms generated in this framework are sensitive to the messenger scale and the gauge couplings, leading to a predictability in the supersymmetric mass spectrum. The review also addresses the generation of Higgs mixing parameters μ and Bμ, and the implications for dark matter and cosmology. The models are shown to have a high degree of predictivity, with the supersymmetric mass spectrum determined by the effective supersymmetry-breaking scale, the messenger index, and tanβ. The review highlights the importance of gauge-mediated theories in addressing the naturalness problem and provides a comprehensive overview of their structure and phenomenological features.Gauge-mediated supersymmetry breaking is an alternative to gravity-induced supersymmetry breaking, offering a natural suppression of flavour violations and distinctive phenomenological features. This review discusses the structure, experimental implications, and models of gauge-mediated supersymmetry breaking, emphasizing their ability to generate soft terms without introducing large flavour violations. The theory involves a secluded sector for supersymmetry breaking and a messenger sector that communicates this breaking to the observable sector via gauge interactions. The messenger sector introduces a scale M, which is unrelated to the flavour scale Λ_F, allowing for a natural decoupling of flavour violations. The soft terms generated in this framework are sensitive to the messenger scale and the gauge couplings, leading to a predictability in the supersymmetric mass spectrum. The review also addresses the generation of Higgs mixing parameters μ and Bμ, and the implications for dark matter and cosmology. The models are shown to have a high degree of predictivity, with the supersymmetric mass spectrum determined by the effective supersymmetry-breaking scale, the messenger index, and tanβ. The review highlights the importance of gauge-mediated theories in addressing the naturalness problem and provides a comprehensive overview of their structure and phenomenological features.