RNA is an abbreviation of ribonucleic acid. Messenger RNA, ribosomal RNA (the kind of RNA that constitutes the ribosomes and provides the site for translation), and transfer RNA (whichbrings the amino acids to the ribosomes to make proteins) are its three main forms.

These all act as the intermediaries by which the hereditary code of DNA is converted into proteins. In some viruses, RNA is itself the hereditary molecule.