RNA, or ribonucleic acid, is a molecule essential for various biological roles, including coding, decoding, regulation, and expression of genes. Its structure consists of a single strand made up of nucleotides, which are the building blocks of RNA. Each nucleotide contains a sugar molecule (ribose), a phosphate group, and a nitrogenous base. The four types of nitrogenous bases in RNA are adenine, uracil, cytosine, and guanine. Unlike DNA, which has a double-helix structure, RNA typically forms a single-stranded structure that can fold into complex shapes. This folding allows RNA to perform various functions, such as acting as a messenger between DNA and ribosomes during protein synthesis. The unique structure of RNA enables it to participate in critical cellular processes.