How a chain of hash is built can be found here.
When we make the input to hash in each step of the chain larger, then we can add more data before we hash. We say, we add some payload to the hash. Payload can be anything which you want to be secured by a blockchain. A good example is the bank transaction you performed or every time you lend somebody books or tools or companies may store the serial number of all delivered goods. The opportunities will grow to an endless list.
Some organizational data should also be in the blockchain, like a timestamp, a running serial number for each record and may be a few more things your specific blockchain may need. These are metadata.
A photographer with valuable photos can use the blockchain to proof the origin of the photos. Here comes a problem with the payload size. Modern cameras produce huge raw files. The author’s camera has raw file > 50 megabyte for each photos. Do you want each block of more than 50 megabyte. May be not, especially when you consider the next high end camera may need 80 megabyte for each photos.
A solution is to store the photos somewhere else in a huge server and hash them there (fingerprint). Then you put into your payload the name of the photo, the location where to find it and the hash value of the original photo. By this technique you can store anything from small to huge in your blockchain.
In the diagram the input (magenta) is the payload and eventually some metadata. Metadata like block number may be managed by the blockchain internally and then not required as input. The output (orange) is the next block on your chain. This must be stored at a reliable place, best on multiple locations to prevent disaster in case of a crash. Traditional blockchain need for other reason a huge network, where they share their chain. We will see later that such a network is not required with the backstep blockchain.
It has one drawback so far. If someone copies your chain and manipulates a payload, we know that the hash and all following hashes will be different. But, how can you proof that his chain is manipulated and not yours? Before backstep blockchain there were a few expensive strategies to avoid that. One fundamental strategy is to make cheating technically very work loaded, the second is to involve as many other blockchains as possible. The next page will show what work load and proof-of-work is and how it works.