Reverse transcriptase is an enzyme that synthesizes DNA from an RNA template. This process is known as reverse transcription and is essential for certain viruses, such as HIV, to replicate their genetic material. By converting RNA into DNA, reverse transcriptase allows the viral genome to integrate into the host cell's DNA. In addition to its role in viral replication, reverse transcriptase is also used in laboratory techniques, such as RT-PCR (reverse transcription polymerase chain reaction). This method enables scientists to study gene expression by converting RNA from cells into DNA, which can then be amplified and analyzed for research purposes.