Blockchain - Supply Chain Help

Hey everyone,

Happy new year, I hope you’re well.

I am currently doing the Blockchoin & Bitcoin 101 course and I am struggling to properly understand how the blockchain works, outside of Bitcoin transactions.
For example, I totally understand how the blockchain and the computer networks can verify a transaction, and how this can be open for all to view.
What I don’t understand is how the blockchain can be used to track a whole supply chain? Could somebody explain this to me please.

Thanks a lot. Your help is much appreciated.

Every single transaction is permanently stored in the ledger. For example, think of a component in an assembly such as an air duct for a car, or if you want something a little more imaginative a plastic pituitary gland for a scale model of the human brain.

When that component is first manufactured it will have a barcode, serial number, rfid tag etc… that would be attached to it that would have information on where it was manufactured. So the pituitary gland factory sends a shipment to the brain model assembly plant and each time a pituitary gland is installed it will be scanned/tracked again and this transaction is added to the ledger. So every component in the completed product can be traced all the way to the factory.

Five years later it turns out that the pituitary glands are exploding in classrooms across the country. The transaction ledger can be used to trace the origin of the exploding glands to a factory in Moon Township Pennsylvania, who will be informed that it is their responsibility to finance a recall of their plastic pituitary glands.

So every component used to create a product will have an unique identification marker which will be stored in the ledger.

Another example would be that anyone with permission to the ledger can instantly check on the shipping status of any item.

Thanks for taking time to answer the question, it was really helpful. Much appreciated!

I fully understand how everything is tracked on the ledger, but what stops a manufacturer/individual from adding an additional/alternative ingredient/product and not storing that information on the ledger?

Sorry if this is an absolute noob question, but I really do appreciate the time taken to explain!

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No problem. Never feel bad about asking questions, it’s always better to reach out. I’m still fairly new myself so I understand how this can be a bit daunting sometimes.

When a transaction/entry is made into a ledger, it becomes part of a block which has it’s own unique address which is permanently stored. That address becomes part of the following block, as the first transaction in that block. If a transaction is altered, its hashed address will also be altered. Since each block contains the address of the previous block, making even the slightest change will alter the hashed value/address of every other block after it. This makes that copy of the ledger completely invalid because it does not match all other copies of the ledger. This is how fraud is prevented.