Coinbase was founded in June 2012 by Brian Armstrong and Fred Ehrsam. Blockchain.info co-founder Ben Reeves was part of the original founding team but later parted ways with Armstrong due to a difference in how the Coinbase wallet should operate. The remaining founding team enrolled in the Summer 2012 Y Combinator startup incubator program. In October 2012, the company launched the services to buy and sell bitcoin through bank transfers. In May 2013, the company received a US$5 million Series A investment led by Fred Wilson from the venture capital firm Union Square Ventures. In December 2013, the company received a US$25 million investment, from the venture capital firms Andreessen Horowitz, Union Square Ventures (USV), and Ribbit Capital.
Coinbase requires you to link a bank account, or credit or debit card to your Coinbase account to purchase cryptocurrencies. Using a bank account allows for higher limits ($100/transaction, $2,500/week), but it also takes longer to verify transactions, so you will not see money in your Coinbase wallet for two to four days (depending on your bank). And when selling Bitcoin, once the sale is confirmed, it takes two to four days for the proceeds of that sale to show up in your bank account. With a credit or debit card, limits are lower ($200/week), but you can purchase digital currencies by simply transferring funds from that bank account to the site. For these transactions, Bitcoin shows up in your Coinbase wallet instantaneously. You can also sell Bitcoin to your PayPal account, effectively cashing out, as your Bitcoin will be exchanged for local currency. This transaction, too, is instantaneous.
The other 2% of customer funds, held online, are covered in the event of a breach of Coinbase's online storage. Also, Coinbase holds all customer fiat currency in custodial bank accounts, on behalf of customers. So, if you have fiat currency in Coinbase, in a USD wallet, it is covered by FDIC insurance up to $250,000 (just like a "regular" bank). This protects customer assets (so long as they have been converted to fiat currency) even in the event of Coinbase becoming insolvent.
In 2018 Coinbase launched their independant mobile wallet for iOS and Android. The wallet stores the private keys on the user’s device and only they have access to the funds. This brings Coinbase full circle as it started out as a wallet, transitioned to an exchange only (claiming that they are not a wallet) and now they are offering wallet services again.
Because the blockchain works by verifying transaction history, and this verification process is labor-intensive and slow, only so many transactions can be verified in a certain timespan. So, if you sell your Bitcoin, but the purchase isn’t confirmed by the blockchain network, and the price of the currency changes, the sale won’t process. You'd have to sell your Bitcoin at whatever the new rate is (if you so choose to sell). Also due to the reality of blockchain, as well as for other reasons thus far unidentified, the Coinbase payout system can sometimes be unreliable. There have been reports of extensively delayed payout periods, and bugs sometimes keep the site from running as efficiently as it could or should. A word to the wise: if you are going to invest in and speculate on cryptocurrencies, do so carefully.
With the largest variety of markets and the biggest value - having reached a peak of 18 billion USD - Bitcoin is here to stay. As with any new invention, there can be improvements or flaws in the initial model however the community and a team of dedicated developers are pushing to overcome any obstacle they come across. It is also the most traded cryptocurrency and one of the main entry points for all the other cryptocurrencies. The price is as unstable as always and it can go up or down by 10%-20% in a single day.