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.
It is conceivable that an ASIC device purchased today would still be mining in two years if the device is power efficient enough and the cost of electricity does not exceed it's output. Mining profitability is also dictated by the exchange rate, but under all circumstances the more power efficient the mining device, the more profitable it is. If you want to try your luck at bitcoin mining then this Bitcoin miner is probably the best deal.
That’s why mining pools came into existence. The idea is simple: miners group together to form a “pool” (i.e., combine their mining power to compete more effectively). Once the pool manages to win the competition, the reward is spread out between the pool members depending on how much mining power each of them contributed. This way, even small miners can join the mining game and have a chance of earning Bitcoin (though they get only a part of the reward).
Bitcoin Core is the “official” Bitcoin client and wallet, though isn’t used by many due to slow speeds and a lack of features. Bitcoin Core, however, is a full node, meaning it helps verify and transmit other Bitcoin transactions across the network and stores a copy of the entire blockchain. This offers better privacy since Core doesn’t have to rely on data from external servers or other peers on the network. Bitcoin Core routed through Tor is considered one of the best ways to use Bitcoin privately.
How hard are the puzzles involved in mining? Well, that depends on how much effort is being put into mining across the network. The difficulty of the mining can be adjusted, and is adjusted by the protocol every 2016 blocks, or roughly every 2 weeks. The difficulty adjusts itself with the aim of keeping the rate of block discovery constant. Thus if more computational power is employed in mining, then the difficulty will adjust upwards to make mining harder.  And if computational power is taken off of the network, the opposite happens. The difficulty adjusts downward to make mining easier.
The counterargument is that the blockchain economy is still in its infancy. The “monetized code” that underlies the blockchain concept can be written to carry any sort of information securely, and to administer virtually any kind of transaction, contractual arrangement or other data-driven relationship between humans and their proliferating machines. In the future, supporters say, banks and other large institutions and even governments will run internal blockchains. Consumer product companies and tech companies will use blockchain to manage the “internet of things.” Within this ecosystem, we’ll see a range of cryptos playing different roles, with bitcoin perhaps serving as an investment, while more nimble cryptos can carry out everyday transactions. And the reality is, whatever its flaws, bitcoin’s success and fame thus far makes the whole crypto phenomenon harder to dislodge with every trading cycle.
While senders of traditional electronic payments are usually identified (for verification purposes, and to comply with anti-money laundering and other legislation), users of bitcoin in theory operate in semi-anonymity. Since there is no central "validator," users do not need to identify themselves when sending bitcoin to another user. When a transaction request is submitted, the protocol checks all previous transactions to confirm that the sender has the necessary bitcoin as well as the authority to send them. The system does not need to know his or her identity.
Bitcoin prices saw tremendous activity during 2017, rising several thousand percent over the year. The market has seen some volatility, although many of the dips seen in the cryptocurrency have thus far proven to be good buying opportunities. This trend may or may not continue, but given the outlook for Bitcoin and other cryptocurrencies, the trend could potentially remain higher for a long time to come.
Nakamoto is estimated to have mined one million bitcoins[26] before disappearing in 2010, when he handed the network alert key and control of the code repository over to Gavin Andresen. Andresen later became lead developer at the Bitcoin Foundation.[27][28] Andresen then sought to decentralize control. This left opportunity for controversy to develop over the future development path of bitcoin.[29][28]