Behind the scenes, the Bitcoin network is sharing a massive public ledger called the "block chain". This ledger contains every transaction ever processed which enables a user's computer to verify the validity of each transaction. The authenticity of each transaction is protected by digital signatures corresponding to the sending addresses therefore allowing all users to have full control over sending bitcoins.
Bitcoin is a new currency that was created in 2009 by an unknown person using the alias Satoshi Nakamoto. Transactions are made with no middle men – meaning, no banks! Bitcoin can be used to book hotels on Expedia, shop for furniture on Overstock and buy Xbox games. But much of the hype is about getting rich by trading it. The price of bitcoin skyrocketed into the thousands in 2017.
RISK WARNING: Trading of and investing in cryptocurrencies and other investment products can carry a high level of risk, and may not be suitable for all investors. Trading and investing generally is not appropriate for someone with limited resources and limited investment or trading experience and low risk tolerance. You could sustain a total loss of your investment. Therefore, you should not speculate with capital that you cannot afford to lose. You should always understand that past performance is not necessarily indicative of future performance. Before trading and investing you should carefully consider your objectives, risk tolerance, financial resources, needs, your level of experience and other circumstances. Always seek advice from an independent financial advisor before making any trade or investment.
The only way to defeat these corrupt bastards is not to go along with their game! Start buying gold and silver in any amount, have paper and coin currency in your pocket at all times. Get rid of the credit cards, do business with hard currency and nothing else, don’t get into debt over your head, trade and barter good and services, invest in new gold mine discoveries, be honest with each other, surround yourself with like-minded individuals, protest against your government and its corrupt officials.
By mining, you can earn cryptocurrency without having to put down money for it. That said, you certainly don't have to be a miner to own crypto.  You can also buy crypto using fiat currency (USD, EUR, JPY, etc); you can trade it on an exchange like Bitstamp using other crypto (example: Using Ethereum or NEO to buy Bitcoin); you even can earn it by playing video games or by publishing blogposts on platforms that pay its users in crypto. An example of the latter is Steemit, which is kind of like Medium except that users can reward bloggers by paying them in a proprietary cryptocurrency called Steem.  Steem can then be traded elsewhere for Bitcoin. 
In the context of security, both transparency of the system and immutability of the data stored on blockchain comes into play. Immutability in computer science refers to something that cannot be changed. Once data has been written to a blockchain, it becomes virtually immutable. This doesn’t mean that the data cannot be changed – it just means that it would require extreme computational effort and collaboration to change it and then also, it would be very difficult to cloak it.
A blockchain carries no transaction cost. (An infrastructure cost yes, but no transaction cost.) The blockchain is a simple yet ingenious way of passing information from A to B in a fully automated and safe manner. One party to a transaction initiates the process by creating a block. This block is verified by thousands, perhaps millions of computers distributed around the net. The verified block is added to a chain, which is stored across the net, creating not just a unique record, but a unique record with a unique history. Falsifying a single record would mean falsifying the entire chain in millions of instances. That is virtually impossible. Bitcoin uses this model for monetary transactions, but it can be deployed in many others ways.
If you have ever spent time in your local Recorder’s Office, you will know that the process of recording property rights is both burdensome and inefficient. Today, a physical deed must be delivered to a government employee at the local recording office, where is it manually entered into the county’s central database and public index. In the case of a property dispute, claims to the property must be reconciled with the public index. This process is not just costly and time-consuming — it is also riddled with human error, where each inaccuracy makes tracking property ownership less efficient. Blockchain has the potential to eliminate the need for scanning documents and tracking down physical files in a local recording offices. If property ownership is stored and verified on the blockchain, owners can trust that their deed is accurate and permanent.

The bitcoin blockchain is a public ledger that records bitcoin transactions.[67] It is implemented as a chain of blocks, each block containing a hash of the previous block up to the genesis block[a] of the chain. A network of communicating nodes running bitcoin software maintains the blockchain.[31]:215–219 Transactions of the form payer X sends Y bitcoins to payee Z are broadcast to this network using readily available software applications.