Plant secondary metabolites play a crucial role in defending against various biotic and abiotic stresses. Based on their structure, these metabolites can be broadly classified into two main categories: nitrogen-containing and non-nitrogen-containing compounds. This includes a diverse range of phytochemicals such as glucosinolates, terpenes, alkaloids, terpenoids, flavonoids and phenolics. These tissue-specific metabolites accumulate at different stages of a plant's life cycle, depending on the plant’s needs. Understanding the roles of these compounds under different stress conditions helps in studying their functional significance. In conclusion, recent research highlights the limitations of the current classification systems for plant metabolites. By viewing secondary metabolites as integrated parts of dynamic metabolic networks influenced by environmental stresses, we can gain deeper insights into plant metabolism.