Water-deficit stress induces significant anatomical changes in higher plants, affecting growth, development, and productivity. This review discusses the physiological and molecular mechanisms underlying drought tolerance in plants, emphasizing the importance of understanding plant-water relations and water-stress tolerance at the physiological and molecular levels. Water stress, defined as a reduction in plant water potential and turgor, limits plant growth and productivity, with severe effects on photosynthesis, metabolism, and growth. Drought stress leads to reduced plant biomass, leaf area, and yield parameters, while also affecting root, stem, and leaf morphology. Water-stress tolerance involves cellular biochemistry changes, such as the accumulation of compatible solutes and specific proteins. Post-genomics and metabolomics are crucial for exploring drought-resistant genes, but must be combined with field-based physiological measurements for practical applications. Root length, stem length, and leaf area are significantly affected by water stress, with prolonged stress reducing root biomass and leaf area. Water-use efficiency (WUE) is a key factor in plant productivity, and studies show that drought-tolerant genotypes can maintain higher WUE under water-limited conditions. The review highlights the importance of understanding drought responses in plants, including osmotic adjustment, root system development, and physiological adaptations. Future research should focus on linking physiological and molecular responses to improve drought tolerance in crops, with a particular emphasis on the role of endogenous hormones, redox state, and gene regulation in drought stress. The study of plant drought tolerance is essential for sustainable agriculture and food security in the face of climate change.Water-deficit stress induces significant anatomical changes in higher plants, affecting growth, development, and productivity. This review discusses the physiological and molecular mechanisms underlying drought tolerance in plants, emphasizing the importance of understanding plant-water relations and water-stress tolerance at the physiological and molecular levels. Water stress, defined as a reduction in plant water potential and turgor, limits plant growth and productivity, with severe effects on photosynthesis, metabolism, and growth. Drought stress leads to reduced plant biomass, leaf area, and yield parameters, while also affecting root, stem, and leaf morphology. Water-stress tolerance involves cellular biochemistry changes, such as the accumulation of compatible solutes and specific proteins. Post-genomics and metabolomics are crucial for exploring drought-resistant genes, but must be combined with field-based physiological measurements for practical applications. Root length, stem length, and leaf area are significantly affected by water stress, with prolonged stress reducing root biomass and leaf area. Water-use efficiency (WUE) is a key factor in plant productivity, and studies show that drought-tolerant genotypes can maintain higher WUE under water-limited conditions. The review highlights the importance of understanding drought responses in plants, including osmotic adjustment, root system development, and physiological adaptations. Future research should focus on linking physiological and molecular responses to improve drought tolerance in crops, with a particular emphasis on the role of endogenous hormones, redox state, and gene regulation in drought stress. The study of plant drought tolerance is essential for sustainable agriculture and food security in the face of climate change.