Terrestrial plants evolved different mechanisms of adaptation to drought, a primary survival challenge. While shoot traits, including stomatal closure, have been the major focus in drought research, the role of the hidden organ, the root, has lately been in the limelight. Being the first organ exposed to water scarcity in the soil, the root acts as the drought sensor, relaying the signal to the aerial organs, primarily supplying the drought hormone, abscisic acid, to the shoot. This review encompasses recent genetic screens focussed on root traits, modern approaches of phenotyping root system architecture, and molecular signaling events in roots for drought tolerance. Molecular mechanisms of root responses, including gravitropism and hydropatterning, as well as the intricacies of root-to-shoot communication under drought, are enumerated. The review separately treats root adaptations in extremophytes, including extraordinary root depths and spreads, rain roots to capture moisture from the atmosphere, histomorphological root adaptations including lignification, suberization, and aerenchyma formation, determinate root development in Cactaceae, and root signaling in resurrection plants, phoenixes of the plant kingdom. The vital roles of the rhizomicrobiome in augmenting the root tolerance responses to drought from individual plants to the ecosystem level are elaborated. The review identifies gaps in drought memory research focussed on the roots, and foresees the role of upcoming single-cell omics technologies in identifying specific molecular events in different root cell types under drought. Finally, how the state-of-the-art in root stress biology can be translated into engineering root traits for crop drought tolerance is discussed.