👉 Externs, in the context of computer science and programming languages, are components or parts that are not part of a larger system but can be used independently. These components include variables, functions, classes, and other objects that interact with each other to accomplish tasks. Internally, these components work together to provide functionality and utility for the programmer. However, when they are created by an external program, such as a library or framework, they become part of the larger system and can be used independently.