Bitcoin is an open-source project launched on January 2009.
www.blockchain.info is the most popular bitcoin blockchain explorer (meaning a record of all bitcoin transactions). Blockchain.info is often confused as "the bitcoin blockchain" but it is a company in Luxembourg providing wallet service and other analytical tools for bitcoin.
Bitcoin gained its most publicity in 2017. It sold at a little over $20,000 on December 17th.
There are ever going to be only 21million bitcoins in existence, however many more are lost due to people forgetting or losing their private keys(access to their coins), death or several meager amounts of coins unspent in millions of addresses. This means the circulating amount of bitcoin will be far lesser than 21million.
Bitcoin is the base currency of nearly all recognized altcoins(other "ALTernative COINS", that is not bitcoin). This means to trade other coins on several exchanges, you need bitcoin. A lot of people trade other coins to gain more bitcoin since it is believed to be the most valuable coin.
All newly mined bitcoins remain with the miner(s) who mined them until they decide to sell it or give it out.
Bitcoin has unfortunately become more expensive and slower for transactions while some altcoins have solutions addressing this issue. Some altcoins in this category include forks of bitcoin itself, meaning they have identical historical records. However, the core team developers have constantly b
No entity practically controls bitcoin but there are a lot of people with great influences and this is largely because they adopted the technology early.
Bitcoin is still considered an experiment meaning there are many new possibilities that aren't yet explored and could be implemented on the protocol.
Bitcoin is not just about trading. In recent times, the usage of bitcoin and most other cryptocurrency has been centered around trading. Bitcoin has many use-cases than just that and in the near future, a lot of these features will become implemented.