In molecular biology, an amplicon is a piece of DNA or RNA that is the source and/or product of amplification or replication events. Amplicons can be naturally formed through gene duplication or artificially generated using methods like polymerase chain reactions (PCR) . During artificial amplification, amplicon length is dictated by the experimental goals. Amplicons in general are direct repeat (head-to-tail) or inverted repeat (head-to-head or tail-to-tail) genetic sequences, and can be either linear or circular in structure. Circular amplicons consist of imperfect inverted duplications annealed into a circle and are thought to arise from precursor linear amplicons.

Amplicon sequencing is a highly targeted technique that enables researchers to analyze genetic variations in specific genomic regions using a series of oligonucleotide probes to target and capture regions of interest, followed by high-throughput sequencing. The length of amplicons ranges from 100 bp to 10 Kb. The ultra-deep amplicon sequencing allows variant detection and characterization. Amplicon sequencing is particularly useful for genome targeting and detection of hot-spot mutations, copy number variations, gene fusions, InDels and single-nucleotide polymorphisms (SNPs) .

Analysis of amplicons has been made possible by the development of amplification methods such as PCR, and increasingly by cheaper and more high-throughput technologies for DNA sequencing or next-generation sequencing. DNA sequencing technologies such as next-generation sequencing have made it possible to study amplicons in genome biology and genetics, including cancer genetics research, phylogenetic research, and human genetics. Amplicon sequencing can be successfully applied to a variety of disciplines like nutrition, bacterial metagenomics, gene editing, and clinical research.