Ballistic bitcoin
1/15
Bitcoin rocketed to another record high close of $16,000 on the Luxembourg-based Bitstamp exchange after gaining more than $4,000 in just 48 hours, stoking concerns that a rapidly swelling bubble could be set to burst.
There were huge disparities between prices across different exchanges. On GDAX, one of the biggest, the price reached $19,500.
Here are some facts that you might not know about the largest and best-known cryptocurrency.
How many are there?
2/15
Bitcoin's supply is limited to 21 million - a number that is expected to be reached around the year 2140.
So far, around 16.7 million bitcoins have been released into the system, with 12.5 new ones released roughly every 10 minutes via a process called "mining", in which a global network of computers competes to solve complex algorithms in reward for the new bitcoins.
Energy Drain
3/15
These mining computers require a vast amount of energy to run. As the price increases, more miners enter the market, driving up the energy consumption further.
A recent estimate by tech news site Motherboard put the energy cost of a single bitcoin transaction at 215 kilowatt-hours, assuming that there are around 300,000 bitcoin transactions per day.
That's almost enough energy as the average American household consumes in a whole week.
Bits of Bitcoin
4/15
If you want to buy bitcoin, you do not need to buy a whole one. Bitcoin's smallest unit is a Satoshi, named after the elusive creator of the cryptocurrency, Satoshi Nakamoto.
One Satoshi is one hundred-millionth of a bitcoin, making it worth around $0.0002 at current exchange rates.
Bitcoin Billionaires
5/15
Bitcoin has performed better than every central bank-issued currency in every year since 2011 except for 2014, when it performed worse than any traditional currency.
So far in 2017, it is up more than 1,400 percent. If you had bought $1,000 of bitcoin at the start of 2013 and had never sold any of it, you would now be sitting on around $1.2 million.
Many people consider bitcoin to be more of a speculative instrument than a currency, because of its volatility, high transaction fees, and the fact that relatively few merchants accept it.
Exchange Heists
6/15
More than 980,000 bitcoins have been stolen from exchanges, either by hackers or insiders.
That's a total of more than $15 billion at current exchange rates. Few have been recovered.
Mystery Creator
7/15
Despite many attempts to find the creator of bitcoin, and a number of claims, we still do not know who Satoshi Nakamoto is, or was.
Australian computer scientist and entrepreneur Craig Wright convinced some prominent members of the bitcoin community that he was Nakamoto in May 2016, but he then refused to provide the evidence that most of the community said was necessary.
It is not clear whether Satoshi Nakamoto, assumed to be a pseudonym, was a name used by a group of developers or by one individual. Nor is it clear that Nakamoto is still alive - the late computer scientist Hal Finney's name is sometimes put forward.
Developer Nick Szabo has denied claims that he is Nakamoto, as has tech entrepreneur Elon Musk more recently.