Given a document, find the main entity about whom the author is writing. Write the full name if mentioned in the text. Note that URLs in the text have been replaced with [Link].

Bitcoin hit a record high of $16 623 per coin on Thursday  December 7. Two years ago  the idea of buying the virtual currency even at that price was laughable. After a rapid rise in value in 2013  the cryptocurrency's value more than halved by mid-2015. At its lowest point  one bitcoin was equal to about $230. Given the currency's covert nature  the average person still may not understand how buying and selling actually works. Using the app Coinbase  which lets anyone trade bitcoins for a small fee  we decided to find out. A brief warning: If you're going to do this  tell your bank you're about to buy bitcoin. More on that later. And to read more about blockchain  the technology powering bitcoin  click here. View As: One Page Slides
This is what the Coinbase app looks like on an iPhone.
However  Coinbase's interface makes it simple to enter the basic personal information it needs to create your account.
The final step before entering my financial information was two-step verification for security  which  Coinbase  quickly sent to my phone.
To sell the bitcoin   Coinbase  only allows users to pair  their  bank account with the app; a credit or debit card won't suffice.
Since  Coinbase  wasn't linked to my bank account  the transaction needs a few days to process before the money is transferred.
Coinbase