Oligos or oligonucleotides are short single strands of synthetic DNA or RNA. They are made by a process known as solid-phase chemical synthesis. During this process, a growing chain of nucleotides is formed by adding the four nucleic acids A, T, C, and G one at a time. In the process of adding one nucleotide to another, the chain grows in the 3’ to 5’ direction. The process results in a full-length oligo.

Oligoes serve as the starting point for a wide range of molecular biology and synthetic biology applications including genetic testing, disease diagnosis, and forensic research.