What is a Bug?

A bug, in the context of software development, is a defect or an error in the code that prevents the program from functioning as intended. Or, you know, just makes it do weird stuff.

• A batch processing bug: when your program processes 37% of the records, but claims it's 100% complete.
• A cascading bug: when your program crashes, but only after 5 levels of recursive function calls.
• A logic bug: when your program does exactly what it's supposed to do, but for the wrong reasons.