In software development, a dependency is a piece of software that another piece of software relies on in order to function. An application’s dependencies are the external components that the application needs in order to work. These can include libraries, frameworks, and other software packages that the application uses. — For example, if an application is written in Python and uses the Django web framework, then Django would be a dependency of the application. In order to run the application, the Django library would need to be installed on the system.