When a program does not behave in the way it is supposed to, we say the program contains a bug. A bug is not a compilation error — compilation errors are relatively easy to clear, because the compiler tells you where the problems are. By contrast, bugs are errors that happen during program execution and they can be hard (sometimes very hard!) to detect.
Programa bat behar bezala ez dabilenean, programa horrek programazio-erroreak dituela esaten dugu. Horiek ez dira konpilazio-erroreak; konpilatzaileak arazoa non dagoen esaten duenez, nahiko erraz konpontzen dira konpilazio-erroreak. Gainera, programa exekutatzean gertatzen dira programazio-erroreak, eta detektatzen zailak (oso zailak) izaten dira.