In computer science and software development, a Library is a bundle of resources (mostly per-written code that provides methods and properties) that can be imported in a new project.
A Software Library helps save time on writing the same functionality that have already been implemented by someone else.
Companies and engineers today provide many open source libraries that one can use in their project, this way developing complex projects become simpler and more efficient.
Where can I use a Software Library ?
For example, when developing an application that requires complex mathematical calculations, a developer can either write the code or choose to import a mathematics library to the application to eliminate the need for writing complex functions to achieve those calculations. This saves time a lot of time as well as need for testing, as most libraries are extensively tested already and used by lot of people and companies.
When you import a library into your project, all the available functions in the library can just be called implicitly without the need of defining them explicitly.
Examples of popular libraries