Lesson 8: The very first computer BUG in history

A computer bug is a flaw, error, malfunction, or mistake inside a computer program that either hinders it from functioning properly or generates an incorrect result. Bugs are caused by human errors in the source code or the design of a program.

It is often said that on September 9, 1947, a group of computer engineers at Harvard University revealed the first computer bug in history, a moth entrapped in their machine. In fact, the term "bug" was invented before this. The term has been in use since the early 1800s, when Thomas Edison used it to describe an issue with one of his telephone designs.

The vast majority of software bugs are fairly simple to fix once the root cause is identified, such as failure to correctly initialize a variable or comparing against the incorrect value. Occasionally, a bug gives a programmer indigestion for days or weeks because it uncovers a basic design weakness in the software system and necessitates an extensive code overhaul, but this is extremely rare.