Ligases are a type of enzyme that play a crucial role in the process of joining two molecules together. They facilitate the formation of bonds between these molecules, often using energy derived from the breakdown of ATP (adenosine triphosphate). This process is essential in various biological functions, including DNA replication and repair. In the context of molecular biology, ligases are particularly important for connecting fragments of DNA. For example, during the replication of DNA, ligases help seal gaps between Okazaki fragments on the lagging strand, ensuring that the genetic material is continuous and stable.