Online Credit Card Processing
A common use for computers these days is online credit card processing. From the credit card machine you swipe your card through when picking up groceries at the store to online ecommerce and mail order, a computer is involved at every stage of every transaction.
These computers and their software are specialised equipment. A whole new business sector has sprung up in the last thirty years for credit card merchant accounts. Without this software the world would grind to a halt and economies would fail.