A Code Library is a collection of pre-written code that developers can use to simplify their programming tasks. It contains functions, classes, and routines that can be reused across different projects, saving time and effort. By using a code library, programmers can avoid rewriting common code and focus on building unique features for their applications. Code libraries can be specific to a programming language, such as Python or JavaScript, and may be open-source or proprietary. Popular examples include jQuery for web development and NumPy for numerical computing in Python. These libraries help streamline the development process and enhance productivity.