Moths are a paraphyletic group of insects that includes all members of the order Lepidoptera that are not butterflies, with moths making up the vast majority of the order. There are thought to be approximately 160,000 species of moth, many of which have yet to be described. Most species of moth are nocturnal, but there are also crepuscular and diurnal species.

A software bug is an error, flaw or fault in computer software that causes it to produce an incorrect or unexpected result, or to behave in unintended ways. The process of finding and correcting bugs is termed "debugging" and often uses formal techniques or tools to pinpoint bugs. Since the 1950s some computer systems have been designed to deter, detect or auto-correct various computer bugs during operations.

Most bugs arise from mistakes and errors made in either a program's design or its source code, or in components and operating systems used by such programs. A program with many, or serious, bugs is said to be buggy. Bugs can trigger errors that may have ripple effects. Bugs may have subtle effects, or cause a program to crash, or freeze the computer. Other bugs qualify as security bugs and might, for example, enable a malicious user to bypass access controls in order to obtain unauthorized privileges.Some software bugs have been linked to disasters. Bugs in code that controlled the Therac-25 radiation therapy machine were directly responsible for patient deaths in the 1980s. In 1996, the European Space Agency's US$1 billion prototype Ariane 5 rocket was destroyed less than a minute after launch due to a bug in the on-board guidance computer program. In 1994, an RAF Chinook helicopter crashed, killing 29; this was initially blamed on pilot error, but was later thought to have been caused by a software bug in the engine-control computer. Buggy software caused the early 21st century British Post Office scandal, the most widespread miscarriage of justice in British legal history.In 2002, a study commissioned by the US Department of Commerce's National Institute of Standards and Technology concluded that "software bugs, or errors, are so prevalent and so detrimental that they cost the US economy an estimated $59 billion annually, or about 0.6 percent of the gross domestic product".