You'll earn 6% back at U.S. supermarkets on up to $6,000 a year in spending, plus 6% back on select U.S. streaming services and 3% back at U.S. gas stations and eligible transit. Terms apply. The ...

Ever received a paper token from your next-door paan shop in lieu of a small change, which he would accept the next time you visit him? Imagine that token digitally, and that's your cryptocurrency.