The creator of bitcoin figured out a way to let two entities confidently trade directly with one another, without the need to rely on all these intermediaries. The key is mathematics. As long as we both trust in math, we can be confident the exchange to occur as expected.
Bitcoin uses public key cryptography and an innovative approach to bookkeeping to achieve the authorization, balance verification, prohibition on double spending, delivery of assets and record inalterability described above. And it happens in near real time at no cost.
Cryptography ensures authorization. You need a private key to transact. And your key is complex enough that it would take the best computer longer than the earth has existed to crack it. In other words, it’s essentially unhackable.
Bitcoin Transactional properties:
1.) Irreversible: After confirmation, a transaction can‘t be reversed. By nobody. And nobody means nobody. Not you, not your bank, not the president of the United States, not Satoshi, not your miner. Nobody. If you send money, you send it. Period. No one can help you, if you sent your funds to a scammer or if a hacker stole them from your computer. There is no safety net.
2.) Pseudonymous: Neither transactions or accounts are connected to real world identities. You receive Bitcoins on so-called addresses, which are randomly seeming chains of around 30 characters. While it is usually possible to analyze the transaction flow, it is not necessarily possible to connect the real-world identity of users with those addresses.
3.) Fast and global: Transaction is propagated nearly instantly in the network and are confirmed in a couple of minutes. Since they happen in a global network of computers they are completely indifferent of your physical location. It doesn‘t matter if I send Bitcoin to my neighbour or to someone on the other side of the world.
4.) Secure: Bitcoin funds are locked in a public key cryptography system. Only the owner of the private key can send cryptocurrency. Strong cryptography and the magic of big numbers makes it impossible to break this scheme. A Bitcoin address is more secure than Fort Knox.
5.) Permissionless: You don‘t have to ask anybody to use cryptocurrency. It‘s just a software that everybody can download for free. After you installed it, you can receive and send Bitcoins or other cryptocurrencies. No one can prevent you. There is no gatekeeper.