The article provides a comprehensive overview of cytokinin, a plant hormone that plays a crucial role in various physiological processes and responses to the environment. Cytokinins were first identified in the 1950s and have since been linked to growth, development, and stress responses in plants. The article reviews the historical context of cytokinin's discovery and the recent advancements in understanding its biosynthesis, metabolism, transport, and signaling pathways. **Biosynthesis and Metabolism:** Cytokinins are primarily synthesized in roots and shoots, with different types of cytokinins being produced in specific tissues. The biosynthesis involves the linking of an isoprene moiety to adenosine, followed by hydroxylation and further modifications. Key enzymes in this process include isopentenyl transferase (IPT) and cytochrome P450 monooxygenases (CYP735A). Cytokinins are metabolized by cytokinin oxidases (CKX), which degrade them, and by glucosyltransferases (UGT) that add glucose moieties, affecting their stability and activity. **Transport:** Cytokinins are transported within plants through the xylem and phloem. The transporters involved include members of the EQUILIBRATIVE NUCLEOSIDE TRANSPORTERS (ENT) family, ATP-BINDING CASSETTE TRANSPORTER G (ABCG) family, PURINE PERMEASES (PUPs), and SWEET family. These transporters facilitate the long-distance transport of cytokinins between different plant parts. **Signaling Pathway:** The cytokinin signaling pathway involves a two-component system with histidine kinase (HK) receptors and response regulators (RRs). HK receptors bind cytokinins and activate a phosphorelay, transferring phosphate groups to RRs. Type-B RRs are transcription factors that mediate the initial response to cytokinin, while type-A RRs act as negative regulators. The signaling pathway is regulated by histidine-containing phosphotransfer proteins (AHPs) and pseudo-Histidine phosphotransfer proteins (PHPs), which modulate the activity of RRs. **Roles in Plant Development and Responses to Stress:** Cytokinins are essential for cell division, meristem maintenance, and organogenesis. They regulate the activity of transcription factors like WUS and SHOOT MERISTEMLESS, which control stem cell fate and meristem size. Cytokinins also influence vascular and cambium development, acting in concert with auxin to control the differentiation of xylem and phloem tissues. Additionally, cytokinins play a role in stress responses, such as drought tolerance and salt stress, by regulating gene expression and cellular processes. The article highlights the importance of cytokinin in plant growth and development, emphasizing its complex regulatory roles and the ongoing research efforts to understand its mechanisms.The article provides a comprehensive overview of cytokinin, a plant hormone that plays a crucial role in various physiological processes and responses to the environment. Cytokinins were first identified in the 1950s and have since been linked to growth, development, and stress responses in plants. The article reviews the historical context of cytokinin's discovery and the recent advancements in understanding its biosynthesis, metabolism, transport, and signaling pathways. **Biosynthesis and Metabolism:** Cytokinins are primarily synthesized in roots and shoots, with different types of cytokinins being produced in specific tissues. The biosynthesis involves the linking of an isoprene moiety to adenosine, followed by hydroxylation and further modifications. Key enzymes in this process include isopentenyl transferase (IPT) and cytochrome P450 monooxygenases (CYP735A). Cytokinins are metabolized by cytokinin oxidases (CKX), which degrade them, and by glucosyltransferases (UGT) that add glucose moieties, affecting their stability and activity. **Transport:** Cytokinins are transported within plants through the xylem and phloem. The transporters involved include members of the EQUILIBRATIVE NUCLEOSIDE TRANSPORTERS (ENT) family, ATP-BINDING CASSETTE TRANSPORTER G (ABCG) family, PURINE PERMEASES (PUPs), and SWEET family. These transporters facilitate the long-distance transport of cytokinins between different plant parts. **Signaling Pathway:** The cytokinin signaling pathway involves a two-component system with histidine kinase (HK) receptors and response regulators (RRs). HK receptors bind cytokinins and activate a phosphorelay, transferring phosphate groups to RRs. Type-B RRs are transcription factors that mediate the initial response to cytokinin, while type-A RRs act as negative regulators. The signaling pathway is regulated by histidine-containing phosphotransfer proteins (AHPs) and pseudo-Histidine phosphotransfer proteins (PHPs), which modulate the activity of RRs. **Roles in Plant Development and Responses to Stress:** Cytokinins are essential for cell division, meristem maintenance, and organogenesis. They regulate the activity of transcription factors like WUS and SHOOT MERISTEMLESS, which control stem cell fate and meristem size. Cytokinins also influence vascular and cambium development, acting in concert with auxin to control the differentiation of xylem and phloem tissues. Additionally, cytokinins play a role in stress responses, such as drought tolerance and salt stress, by regulating gene expression and cellular processes. The article highlights the importance of cytokinin in plant growth and development, emphasizing its complex regulatory roles and the ongoing research efforts to understand its mechanisms.