Which of the following best defines a syntax error?

A syntax error specifically refers to a mistake in the structure of code that prevents the program from being compiled or interpreted correctly. These errors arise from not following the language rules governing how code must be written, such as missing punctuation, using incorrect keywords, or misplacing brackets. Syntax errors are detected during the compilation process, meaning that they must be resolved for the code to execute properly.

The focus on the structure of the program code is crucial, as it dictates how the code is parsed and understood by the compiler or interpreter. If the structure is incorrect, the tool will not be able to proceed with executing the program. This is distinct from other types of errors that may occur during runtime or relate to design flaws rather than the written syntax of the code itself.