Applications constantly undergo modifications, bug fixes, and customization. Programmers often remove pieces of obsolete code that use a variable while leaving the declaration of that variable intact. A clever compiler can detect an unused variable and issue a warning message. However, not every compiler does that, and even compilers that do so are often configured to suppress warnings to minimize “noise.” The problem with such unused variables is that they clutter up the code and might mislead future maintainers of the code. For this reason, you should add an additional phase to your code review: “elimination of dead declarations.” You may be surprised by how many such dead declarations exist in every sizable project.