Single-stranded DNA, or ssDNA, is a type of nucleic acid that consists of a single strand of DNA rather than the typical double helix structure found in most organisms. It plays a crucial role in various biological processes, including replication and transcription, where it serves as a template for synthesizing RNA or complementary DNA. ssDNA is often used in molecular biology techniques, such as PCR (polymerase chain reaction) and DNA sequencing. Its unique properties allow researchers to study genetic material more easily and develop applications in fields like genetics, forensics, and biotechnology.