An array of miners! Nothing more to say.
Bitcoin is not regulated by a central authority. Instead, it's backed by millions of computers across the world called “miners.” Bitcoin mining is the process of updating the ledger of Bitcoin transactions known as the blockchain. Bitcoin miners are spread out across the world and record transaction data in a public list that can be accessed by anyone, even you.
• 100% combed and ring-spun cotton (heather colors contain polyester)
• Fabric weight: 4.2 oz (142 g/m2)
• Shoulder-to-shoulder taping