This review article discusses the mechanisms of salinity tolerance in plants, focusing on physiological, biochemical, and molecular aspects. Salinity is a major abiotic stress that limits plant growth and productivity due to increasing use of poor quality water for irrigation and soil salinization. Plants adapt to salinity stress through complex physiological traits, metabolic pathways, and molecular or gene networks. Understanding these mechanisms is crucial for developing salt-tolerant plant varieties in saline areas. Recent research has identified various adaptive responses to salinity stress at molecular, cellular, metabolic, and physiological levels, although the mechanisms underlying salinity tolerance are not fully understood. The article reviews major research advances on biochemical, physiological, and molecular mechanisms regulating plant adaptation and tolerance to salinity stress. It discusses the physiological and biochemical mechanisms of salt tolerance, including ion homeostasis, compatible solute accumulation, antioxidant regulation, roles of polyamines, and nitric oxide. It also covers the role of hormones in salinity tolerance, such as abscisic acid (ABA), salicylic acid (SA), and brassinosteroids (BR). The review also explores transcriptional regulation and gene expression of salinity tolerance, highlighting the importance of transcription factors and their roles in stress responses. Additionally, it discusses the role of alternative splicing and SUMOylation in plant responses to salinity stress. The article concludes by emphasizing the need for further research to fully understand the complex mechanisms of salinity tolerance in plants.This review article discusses the mechanisms of salinity tolerance in plants, focusing on physiological, biochemical, and molecular aspects. Salinity is a major abiotic stress that limits plant growth and productivity due to increasing use of poor quality water for irrigation and soil salinization. Plants adapt to salinity stress through complex physiological traits, metabolic pathways, and molecular or gene networks. Understanding these mechanisms is crucial for developing salt-tolerant plant varieties in saline areas. Recent research has identified various adaptive responses to salinity stress at molecular, cellular, metabolic, and physiological levels, although the mechanisms underlying salinity tolerance are not fully understood. The article reviews major research advances on biochemical, physiological, and molecular mechanisms regulating plant adaptation and tolerance to salinity stress. It discusses the physiological and biochemical mechanisms of salt tolerance, including ion homeostasis, compatible solute accumulation, antioxidant regulation, roles of polyamines, and nitric oxide. It also covers the role of hormones in salinity tolerance, such as abscisic acid (ABA), salicylic acid (SA), and brassinosteroids (BR). The review also explores transcriptional regulation and gene expression of salinity tolerance, highlighting the importance of transcription factors and their roles in stress responses. Additionally, it discusses the role of alternative splicing and SUMOylation in plant responses to salinity stress. The article concludes by emphasizing the need for further research to fully understand the complex mechanisms of salinity tolerance in plants.