Illiquidity. This is mostly moot due to Bitcoin’s $47 market cap but it still makes users sweat. It’s highly unlikely that Bitcoin’s price would plummet and you’d be unable to take action, but it’s still unsettling.  As more investors invest, however, illiquidity becomes a negligible risk, as there will likely always be a buyer for Bitcoins waiting.
Protect your address: Although your user identity behind your address remains anonymous, Bitcoin is the most public form of transaction with anyone on the network seeing your balances and log of transactions. This is one reason why you should change Bitcoin addresses with each transaction and safeguard your address. You can also use multiple wallets for different purposes so that your balance and transaction history remain private from those who send you money.

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.

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.
Armory is the most mature, secure and full featured Bitcoin wallet but it can be technologically intimidating for users. Whether you are an individual storing $1,000 or institution storing $1,000,000,000 this is the most secure option available. Users are in complete control all Bitcoin private keys and can setup a secure offline-signing process in Armory.
As I mentioned earlier, Bitcoin is not like a typical currency that you keep in your bank. You are responsible for the security of your Bitcoins and that’s why you keep it in a wallet that you have 100% control over. This is done by having the ownership of seed word or private key.  For the first timer, it may sound very technical, but it is actually easy to understand and learn.
Yes. There are public blockchains, which are open to anyone to send transactions on or to verify or observe what’s happening at any given time. Two of the most popular public blockchains are the Bitcoin blockchain and one for Ethereum, another cryptocurrency. There are also companies, such as Aion, which debuted in April as a way to help other companies build their own blockchain products and services. (TechCrunch likened it to what Linux has done as an open-source platform for operating systems.)
In Bitcoin, it’s like every organic food store has someone out front, offering free samples. Also, there’s a library everywhere you look, but only a few of those libraries have any good information. The largest traders would benefit a great deal if everyone just jumped blindly into Bitcoin, investing large chunks of their life savings in the process. That would be just fine by them, but it’s unlikely to happen. More likely, people are going to get involved with Bitcoin either by necessity, by chance or because someone was willing to give them a few bitcoins to get started with.
In the Bitcoin network, the blockchain is not only shared and maintained by a public network of users — it is also agreed upon. When users join the network, their connected computer receives a copy of the blockchain that is updated whenever a new block of transactions is added. But what if, through human error or the efforts of a hacker, one user’s copy of the blockchain manipulated to be different from every other copy of the blockchain?
Located in Brooklyn, Consensys is one of the foremost companies globally that is developing a range of applications for Ethereum. One project they are partnering on is Transactive Grid, working with the distributed energy outfit, LO3. A prototype project currently up and running uses Ethereum smart contracts to automate the monitoring and redistribution of microgrid energy. This so-called “intelligent grid” is an early example of IoT functionality.
Do not keep too many bitcoins in any one wallet at once. Part of the reason bitcoin wallets are referred to as wallets is because it's important to think of your bitcoins as cash. Just as you wouldn't go shopping with thousands of dollars in your wallet, it is probably unwise to store large amounts of bitcoins in your wallet. Keep some bitcoins on your mobile, online, or desktop wallet but store other amounts in a more secure environment.[10]

Bitcoin has both advantages and disadvantages. Advantages include the ability to choose your own fees, easily accept payment from people who do not have credit cards, and send payment without tying your personal information to the transaction.[32] Disadvantages include that it is a very new form of currency, acceptance of it is still limited, and the anonymity of transactions means you do not know with whom you're dealing.[33]
In Person: Over-the-counter platforms such as CoinCola or LocalBitcoins are resources to find people in your area to trade bitcoins with. Trust and security can be a concern, which is why it's recommended you transact in a public place, and not necessarily with large amounts of cash. Some of those platforms, such as CoinCola, will allow its users to upload an ID proof. In this case, you will be able require the ID proof of your trade partner for added security.
Keep in mind that if you’re not sure what you’re doing when claiming a forkcoin you could end up losing your Bitcoins. So for most non technical users it would better to pass on a fork and keep your Bitcoins safe. Other alternatives include companies that claim the coins for you and take a commission – but this could easily turn into a scam that runs away with you money.
Although Bitcoin is homogenous (the same everywhere in the world), its price varies across countries and even exchanges within the same country, giving a rise to arbitrage opportunities. At one point in 2017, the Bitcoin price in South Korea was trading at a 35% premium and in India, a 20% to 25% premium. The demand and supply conditions result in some aberrations in its price.
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.
David Golumbia says that the ideas influencing bitcoin advocates emerge from right-wing extremist movements such as the Liberty Lobby and the John Birch Society and their anti-Central Bank rhetoric, or, more recently, Ron Paul and Tea Party-style libertarianism.[126] Steve Bannon, who owns a "good stake" in bitcoin, considers it to be "disruptive populism. It takes control back from central authorities. It's revolutionary."[127]
Mining is a record-keeping service done through the use of computer processing power.[e] Miners keep the blockchain consistent, complete, and unalterable by repeatedly grouping newly broadcast transactions into a block, which is then broadcast to the network and verified by recipient nodes.[67] Each block contains a SHA-256 cryptographic hash of the previous block,[67] thus linking it to the previous block and giving the blockchain its name.[3]:ch. 7[67]