What kind of error prevents a program from being compiled?

The type of error that prevents a program from being compiled is a compiler error. These errors occur when the code violates the syntax rules of the programming language, making it impossible for the compiler to translate the source code into executable code. Compiler errors typically arise from issues such as missing semicolons, unmatched parentheses, or the use of undeclared variables. Because these issues must be resolved for the compiler to produce an executable program, they directly impede the compilation process.

While syntax errors are indeed a specific type of compiler error, the broader category encompasses any grammatical mistake or rule violation that leads to compilation failure. Other types of errors, such as logic errors and run-time errors, occur after compilation; logic errors emerge from flaws in the program's design leading to incorrect behavior, while run-time errors happen during the execution of a program, often causing it to crash or misbehave.