Nucleosides, nucleotides, and their analogues are fundamental building blocks in the field of biochemistry and pharmaceuticals. Nucleosides consist of a purine or pyrimidine base covalently attached to a pentose sugar, typically deoxyribose or ribose. Nucleotides further include one or more phosphate groups attached to the 5′-hydroxyl group of the pentose sugar in nucleosides. These compounds are crucial for various biological processes, including DNA and RNA synthesis, gene expression regulation, and energy transfer. Nucleoside analogues have gained significant attention due to their potential applications as antiviral and anticancer agents. For instance, azidothymidine (AZT) is a well-known nucleoside analogue used in the treatment of HIV. Research into these compounds continues to explore new functionalities and therapeutic potentials. With advancements in synthesis techniques and molecular biology, nucleosides, nucleotides, and their analogues are being developed for diverse applications ranging from targeted drug delivery systems to diagnostic tools.