Poloniex was once the best cryptocurrency exchanges, before competitors like Bittrex starting offering superior services. Nevertheless Poloniex went through extremely fast traffic growth since the demise of its rival Cryptsy in 2016, and especially since the recent altcoin bubble of early 2017. Traffic has grown from 33 million monthly visits in November 2017 to 66 million in December 2017. Poloniex has the nicest trading interface out there, both for mobile and desktop users this will work wonders. Please note that because Poloniex is a pure "crypto" exchange, it is not possible to deposit government (fiat) currency. You'll need to first buy bitcoin elsewhere, and then deposit it to be able to tade. I've written a full analysis of Poloniex, further exploring the founders, users, security, fees, history, and alternatives.
Acknowledgment, Acceptance of all Risks and Disclaimer of Warranties and Liabilities THE USER EXPRESSLY KNOWS AND AGREES THAT THE USER IS USING THE Ethereum PLATFORM AT THE USER’S SOLE RISK. THE USER REPRESENTS THAT THE USER HAS AN ADEQUATE UNDERSTANDING OF THE RISKS, USAGES AND INTRICACIES OF CRYPTOGRAPHIC TOKENS AND BLOCKCHAIN-BASED OPEN SOURCE SOFTWARE, ETH PLATFORM AND ETH. THE USER ACKNOWLEDGES AND AGREES THAT, TO THE FULLEST EXTENT PERMITTED BY ANY APPLICABLE LAW, THE DISCLAIMERS OF LIABILITY CONTAINED HEREIN APPLY TO ANY AND ALL DAMAGES OR INJURY WHATSOEVER CAUSED BY OR RELATED TO RISKS OF, USE OF, OR INABILITY TO USE, ETH OR THE Ethereum PLATFORM UNDER ANY CAUSE OF ACTION WHATSOEVER OF ANY KIND IN ANY JURISDICTION, INCLUDING, WITHOUT LIMITATION, ACTIONS FOR BREACH OF WARRANTY, BREACH OF CONTRACT OR TORT (INCLUDING NEGLIGENCE) AND THAT NEITHER Stiftung Ethereum NOR ETHEREUM TEAM SHALL BE LIABLE FOR ANY INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY OR CONSEQUENTIAL DAMAGES, INCLUDING FOR LOSS OF PROFITS, GOODWILL OR DATA. SOME JURISDICTIONS DO NOT ALLOW THE EXCLUSION OF CERTAIN WARRANTIES OR THE LIMITATION OR EXCLUSION OF LIABILITY FOR CERTAIN TYPES OF DAMAGES. THEREFORE, SOME OF THE ABOVE LIMITATIONS IN THIS SECTION MAY NOT APPLY TO A USER. IN PARTICULAR, NOTHING IN THESE TERMS SHALL AFFECT THE STATUTORY RIGHTS OF ANY USER OR EXCLUDE INJURY ARISING FROM ANY WILLFUL MISCONDUCT OR FRAUD OF Stiftung Ethereum.
An increase in cryptocurrency mining increased the demand of graphics cards (GPU) in 2017.[37] Popular favorites of cryptocurrency miners such as Nvidia’s GTX 1060 and GTX 1070 graphics cards, as well as AMD’s RX 570 and RX 580 GPUs, doubled or tripled in price – or were out of stock.[38] A GTX 1070 Ti which was released at a price of $450 sold for as much as $1100. Another popular card GTX 1060's 6 GB model was released at an MSRP of $250, sold for almost $500. RX 570 and RX 580 cards from AMD were out of stock for almost a year. Miners regularly buy up the entire stock of new GPU's as soon as they are available.[39]
In the zero-sum game that cryptocurrency has become, one man’s free money is another man’s headache. In the Mid-Columbia Basin, the latter category includes John Stoll, who oversees Chelan County Public Utility District’s maintenance crews. Stoll regards people like Benny as “rogue operators,” the utility’s term for small players who mine without getting proper permits and equipment upgrades, and whose numbers have soared in the past 12 months. Though only a fraction of the size of their commercial peers, these operators can still overwhelm residential electric grids. In extreme cases, insulation can melt off wires. Transformers will overheat. In one instance last year, the utility says, a miner overloaded a transformer and caused a brush fire.

If your objective is to earn substantial money as a second income, then you are better off purchasing cryptocoins with cash instead of mining them, and then tucking them away in the hopes that they will jump in value like gold or silver bullion. If your objective is to make a few digital bucks and spend them somehow, then you just might have a slow way to do that with mining.
Cryptography is an art, not a science. And the state of the art can advance over time. Advances in code cracking, or technical advances such as the development of quantum computers, could present risks to cryptocurrencies and the Ethereum Platform, which could result in the theft or loss of ETH. To the extent possible, Stiftung Ethereum intends to update the protocol underlying the Ethereum Platform to account for any advances in cryptography and to incorporate additional security measures, but it cannot predict the future of cryptography or guarantee that any security updates will be made in a timely or successful manner.
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