Bitcoin is the first digital currency and was created to give people a choice other than government printed money. The promise of Bitcoin was to create only up to 21 million coins and never inflate the supply more than that. Bitcoin is designed to release the 21 million bitcoins over 130 years.
The release schedule is to release 2.628 million bitcoins per year (50 every 10 minutes), for the first 4 years.After the first 4 years the amount of bitcoins issued is cut in half to 1.314 million per year (25 every 10 minutes), for the next 4 years; and then after another 4 years the amount of bitcoins is cut in half again. The supply of bitcoins created is cut in half every 4 years, until no bitcoins are mined after the year 2140.That is how the Bitcoin protocol is programmed to release bitcoins over time, and unless all users on the network agree to change it, it will never change.
The reason it was programmed with a set release schedule from the start is so that the currency could not be inflated the same way central banks of national governments can inflate their national currency. The limited issuance of the network allows holders of bitcoin to have a great store of value. The Bitcoin issuance rate has gone by with no issues for the last 9 years, except for one incident.
On August 15th 2010, less than a year after Bitcoin was created, a bug in the Bitcoin protocol was exploited and 184 billion bitcoins were created. Almost 10,000 times more bitcoins than should ever exist were created in one episode. Luckily the bug was found really quickly and the whole community, which was pretty small at the time, upgraded and patched the bug, removing the 184 billion bitcoins created.
There is another failsafe on the bitcoin protocol that would help in case something similar happened again. When someone creates bitcoin they are not able to spend them for 20 hours (120 blocks), so like in this case whoever created the 184 billion bitcoins never even had a chance to spend them because the bug was fixed within 8 hours.
The reason these 184 billion bitcoins could be created was because of a thing called “value overflow”. It is a bit technical, but here is a simplified version:When a computer program uses numbers a maximum size for those numbers is chosen. If a number larger than the maximum established size is used in the program that number can sometimes show as a negative number instead of a really large number.
Because the number of bitcoins sent in that transaction was larger than the maximum established size a number could be on the Bitcoin network, the number appeared as a negative. The function that is supposed to filter out invalid transactions failed because the really large number appeared negative, hence very small, and not a larger number than what should be allowed.
The bug has now been fixed and we do not have to worry about someone creating transactions with really large amounts of bitcoins and flooding the network.
You can read more about the incident here:
Technical term: https://en.bitcoin.it/wiki/Value_overflow_incident
Technical explanation: https://bitfalls.com/2018/01/14/curious-case-184-billion-bitcoin/
Developer real time comments while it happened: https://bitcointalk.org/index.php?topic=822.0