During the sourcing and new product development and manufacturing process you'll receive a BOM (Bill Of Materials) and this document will be adjusted and referred to a lot.
Your BOM is a complete list of parts that make up your product, and the document will usually include supplier, cost, and quantities purchased. It may also include second and third supplier options, too, as redundancies against supply chain disruption.
The BOM may evolve over time, but it's recommended to 'lock' it before production and not to change it, otherwise, the products being made may wind up using non-approved parts that could lead to quality, reliability, and safety issues.
Listen: Learn more about the BOM in this episode of our podcast.