Meet the 21 companies you've never heard of that are battling to control bitcoin

Flashy startups like Coinbase, Circle, Blockchain, and BitPay are some of the most famous companies in bitcoin.
But arguably more important are the miners - individuals and organisations who form the core backbone of bitcoin, ensuring the digital currency's integrity.

Bitcoin runs on a blockchain, a decentralised and public ledger of every transaction made on the network. By offering processing power towards this, users get a chance to win bitcoin - creating an arms race of miners scrambling to assemble ever-more sophisticated and powerful equipment to "mine" new bitcoin.

Some individuals go it alone; others join open "pools" where they combine their resources to improve their odds; some larger companies also have mining efforts. While the #1 spot can change from week to week, we have ranked the biggest mining companies using data covering August 5 to August 12 from bitcoin network analysis company Blocktrail .