What you learned in school
Computer classes taught that 640 kilobytes of memory was more than sufficient for any conceivable computer application. Students learned about memory as a precious, limited resource that would always need to be carefully managed and conserved. Textbooks emphasized efficient programming to work within these memory constraints. The assumption was that software would remain relatively simple and that 640K represented a generous amount of memory that would satisfy computing needs indefinitely.
What we know now
Computer classes taught that 640 kilobytes of memory was more than sufficient for any conceivable computer application. Students learned about memory as a precious, limited resource that would always be carefully managed. Modern computers routinely use gigabytes (thousands of times more) of RAM, and even smartphones have multiple gigabytes of memory. Software applications, operating systems, and multimedia content have grown to take advantage of increased memory availability. The prediction failed to anticipate the exponential growth in software complexity and the decreasing cost of memory components.