Neil MacGregor's book the History of the World in 100 Objects chronicles the things that have had the greatest impact on human history. (The items are listed chronologically, not in order of impact.) Here's how MacGregor describes one of the most recent influential objects, the 99th one on his list:

If you were to ask people which twentieth-century invention had most impact on their daily lives today, instant answers might be their mobile phone or their PC: not many people would think first of the little plastic rectangles that fill their wallets and purses. And yet, since they first emerged in the late 1950s, credit cards and their kin have become part of the fabric of modern life ….

The first general-purpose charge card was the Diners Club card, introduced in 1950. In 1958 the next step came with the appearance of the first real credit card, issued by a bank and generally accepted by large numbers of businesses. This was the BankAmericard, ancestor of Visa, and the first universal credit

According to MacGregor, "credit cards have become the ultimate symbol of economic freedom." But there is a dark side. MacGregor writes, "There is little doubt at all that paying by credit card does increase [our] willingness to spend—often more than [we] can afford."