Aptamers are small, single-stranded nucleic acid molecules that can bind to target molecules with high specificity and affinity. They are often referred to as "chemical antibodies" due to their ability to selectively bind to a wide variety of targets, including proteins, small molecules, and even whole cells. Aptamers are generated through in vitro selection processes known as SELEX (Systematic Evolution of Ligands by Exponential Enrichment), in which a large library of random sequences is screened for binding to a specific target. Aptamers have various applications in research, diagnostic, and therapeutic fields. They can be used as molecular tools to study protein-protein interactions, cell surface markers, and drug targets. In diagnostics, aptamers can be used for detecting biomarkers in various diseases, such as cancer and infectious diseases. In therapeutics, aptamers have the potential to be developed as targeted drugs for treating various conditions by interfering with specific protein functions or pathways. Overall, aptamers offer a promising alternative to traditional antibodies due to their high specificity, stability, and ease of production.