To Organize and optimize the serving of complex JavaScript and CSS code,
AEM provides Client-side Library Folders, which allow you to store your
client-side code in the repository, organize it into categories, and
define when and how each category of code is to be served to the client.
Reference :
https://experienceleague.adobe.com/docs/experience-manager-65/developing/introduction/clientlibs.html?lang=en#how-client-side-libraries-work-in-aem