How blockchain-based startups could replace Uber, Airbnb and other major players in the sharing economy market. Part 4. Blockchains and double-spending.
Blockchain technology solves the issue of double-spending by recording all transactions on the blockchain. When you send funds on the Bitcoin network, your transaction only becomes valid when the network confirms it multiple times. A confirmation of a transaction on a blockchain network means the inclusion of the transaction in a block of the blockchain. Many of the Bitcoin wallets require at least six confirmations for a transaction to become valid, which means that information about the transaction needs to be in six blocks of the Bitcoin blockchain. This means that when you send funds, the record about you doing so becomes a part of the ledger, so if you were to try and send funds multiple times, it would simply not work because the network has a record of you spending the money. The Bitcoin blockchain has information about all the transactions that have occurred on the network since Satoshi Nakamoto launched it in 2009. The network is fully transparent and open to anyone. Its explorer is located at https://blockchain.info. At the top of the homepage of the website, you can see information about the latest blocks of the blockchain (or pages of the ledger). The height of the block means the number of the block in the blockchain. The first block of the Bitcoin network that Satoshi Nakamoto created had the height of one, the second one had the height of two and so on.
Block height parameter is a property of blockchain technology and has nothing to do with finances. On a blockchain network for taxi riders, the blocks would also have height just like blocks on the Bitcoin blockchain do.
The transactions column shows the number of transactions in a block. Again, finance is just one application of blockchain. On a network for apartment rentals, transactions could be about hosts agreeing to rent rooms and apartments. On a blockchain network about cargo movements, transactions could be about a container entering or leaving a port and so on.
When you click on a block of Bitcoin blockchain, you can see all the information about all the transactions that the block contains similarly how you would see records on a page of a ledger.
For example, block #523615 of the Bitcoin blockchain contains information about 839 transactions and you can see it all by scrolling down the page at https://blockchain.info/block/00000000000000000003ec4949e8fc2bbb102ecd60a54e9d5ce4d8c52d5b2641. In the search box on top of the page, you can enter a block #, a transaction number, or some other piece of data and see the information for that data. If it happened on the Bitcoin blockchain at some point since 2009, you will see it on the blockchain explorer.
Accessibility of the blockchain data for everyone
All of this is very different from what happens to the data when a private company such as Uber owns the data. According to an article in Business Insider (source: http://www.businessinsider.com/uber-releases-trip-data-to-public-with-movement-2017-1), Uber has only started sharing data about trips with cities in 2017, eight years after the launch of the company. Uber has been resisting the requests to share the data about the trips on the platform because data is its most valuable asset. For example, giving it to the cities could help cities figure out which parts of the cities need more public transportation, but this is not something Uber would be interested in because if cities were to launch more buses or subway lines, Uber would have less business in those areas.
Having access to data would also allow cities to calculate how long it took to get from one part of a city to a different of the city during different times of day/week/year and make conclusions about congestion and traffic patterns and changes. Again, this is not something that is of interest to a private company making money of transportation, but it is something that a transparent blockchain network could provide.