AASPs or Apple Authorised Service Providers, are outside companies/stores that are authorized by Apple to repair and service Apple products.
The Apple Authorized Service Provider (AASP) program is designed for companies interested in offering in-warranty and out-of-warranty repair service for any Apple product. Qualifying companies can gain access to Apple genuine parts, tools, training, service guides, diagnostics and resources to perform these repairs.– Apple Authorized Service Provider Program (Apple.com)
AASP is a program by Apple to certify businesses that want to provide both warranty and out of warranty repairs as well as receive genuine Apple parts in order to perform those repairs. AASPs are also required to have Apple Certified Technicians to perform repairs.
One thing to note is that Apple does not certify businesses with at-home or mail-in repairs. They require that the one and only method of repairs is for the customer to walk into a physical location.
AASPs are also strictly not allowed to share/sell/give parts, manuals, tools, service guides, and diagnostics.