In 1947, engineers at Harvard found a moth trapped in a relay of the Mark II computer. They taped it into the logbook and wrote 'first actual case of bug being found.' Debugging is the process of finding and fixing errors in code. The term stuck, even though most bugs are not insects.

Bugs range from typos to logic errors to race conditions. A missing semicolon stops compilation. A wrong variable name produces the wrong result. A race condition appears only when two threads run in a certain order. Some bugs are easy to spot. Others take days to reproduce.

Debugging techniques

• Print statements: output values at key points
• Breakpoints: pause execution and inspect state
• Rubber duck debugging: explain the code out loud
• Binary search: narrow down where the bug appears
• Version control: compare working and broken versions

Debugging is detective work. You form hypotheses, test them, and eliminate possibilities. The best debuggers are patient and systematic. They do not guess. They observe.