Bitcoin is the first Digital Cryptocurrency ever created using the Blockchain protocol technology by a group of people or a person called Satoshi Nakamoto. A cryptographic software system that secures each transaction into irreversible blocks and does not allow anyone or anything to duplicate/copy or change any transactions made on the network. There is and there will always be only 21 million Bitcoins in the world. It is impossible to create more.
Using a normal banking system, a bank or the authorities can always go into a transaction and either change, stop, hold, revert or modify it as they want for any reason that they find relevant or that their system find relevant without or with your consent as they wish. A normal banking system (central banks) can also decide to create more money and print it either directly in their system or physically for any reason they want. A dollar is not backed by anything else than your trust into the value of it. Back in 1970, each dollar created needed to be backed by the same value in gold. Since 1970, the United States took off that worldwide rule where a dollar would be backed by the same value of gold into vaults, therefore since then, a dollar is not backed by anything else than your trust into the currency.
With Bitcoin or the Blockchain, it is impossible for anyone to ever change a transaction or create more bitcoins. Either it is intended or not, you can never go back into a transaction and change it. What has been done is done. Nobody owns the Bitcoin network and therefore that makes it impossible to stop it. You cannot call the Bitcoin company to ask for a refund, there is no Bitcoin company, only people who provide a way to make transactions or to acquire Bitcoins, but these companies or entities have no control over the Bitcoin network. That’s why we call it Decentralized.
Nobody owns Bitcoin as a Brand or as a company, the people who makes those transactions possible are called “the miners”, they have powerful computer power, they are based anywhere in the world. Everyone can become a “miner” and buy some computer and be part of the “mining pool” of the bitcoin network. Every miner is rewarded into fractions of Bitcoin for providing computer power to the network and make it possible. Each 10 minutes, a “block” is created and all the miners who helped resolve the mathematical puzzle to create the transactions inside that block that have been requested by users are rewarded by some fractions of Bitcoins.
Every 210,000 blocks, about every 4 years, the reward for resolving a block is cut in half. That’s a rule inside the Bitcoin code, it cannot be changed. Cutting in half the Bitcoin reward for resolving a block each 10 minutes makes the production of Bitcoin lower every 4 years. This makes new Bitcoins rarer. That is one of the reasons why the value of a Bitcoin keeps growing. Since its creation in 2009 the Bitcoin network started rewarding every miners 50 Bitcoins for each blocks resolved (each 10 minutes), in 2013 it dropped to 25 Bitcoins per block, in 2018 it became 12.5 Bitcoins per block and now in may of 2020 it became 6.25 Bitcoins per block, which means that only 900 Bitcoins are created every 24 hours.