The ATM machine, or Automated Teller Machine, is a ubiquitous feature of modern life. It has become a symbol of convenience and financial autonomy and is responsible for making it possible for customers to access their accounts and withdraw cash from their bank accounts 24 hours a day, seven days a week.

The Automated Teller Machine (ATM) is a revolutionary invention that has changed the way people access their money. It is estimated that there are now over 3 million ATMs around the world, with over 500,000 in the US alone. 

But who invented the ATM machine and when?

The history of the ATM machine dates back to the mid-1960s when a small team of engineers at the British bank Barclays began to design the first automatic teller machine. The team was led by John Shepherd-Barron, a Scottish inventor who had worked in the banking industry for a number of years.

Shepherd-Barron’s invention was installed at Barclays Bank in London in 1967, and it was the first ATM to be used by a central bank. The machine allowed customers to withdraw cash using a special card and their personal identification number (PIN).

However, Shepherd-Barron’s invention was not without its problems. The machine was slow and unreliable and vulnerable to theft and fraud. In addition, the machine was limited to withdrawals of only £10 per transaction, which was a paltry sum in those days.

In response to these problems, other inventors began to improve on Shepherd-Barron’s invention. In 1969, Donald Wetzel created a machine that was more sophisticated and reliable, and that allowed customers to withdraw larger amounts of cash. Wetzel’s machine was installed in the United States and became the first ATM used by a major bank in the U.S.

From there, the ATM machine continued to evolve and improve over the years. Innovations such as touch-screen technology, wireless communication, and increased security measures have made ATM machines much more reliable and secure. Today, ATMs are found all over the world and are used by millions of people every day.

So, the answer to 'Who invented the ATM machine and when?' is John Shepherd-Barron, who invented the first ATM in 1967, and Donald Wetzel, who developed a more dependable version in 1969. Together, these two inventors made it possible for ATM machines to become a ubiquitous part of modern life.