Libraries, in general, are created and used
in order to avoid code repetition
They are also helpful in creating simple code that does difficult stuff by abstracting the complex portions of code into handy callable functions or classes
Arduino has a flourishing library ecosystem, which is a fundamental feature that greatly contributed to its popularity
Everybody can contribute to the ecosystem by creating their own library, uploading it on Github and adding it to the Arduino Library Registry
All the available official libraries can be found, organized by topic, on Arduino libraries documentation
Arduino IDE offers an integrated library manager that makes installing and using libraries a trivial task; it can be accessed by clicking on the Library Manager icon in the side tab.
The library manager has a user-friendly graphical interface capable of searching, installing, and managing the version of libraries.