In programming, what does a 'syntax error' indicate?

A syntax error indicates that there is a mistake in the code that violates the language's grammar rules. This is a fundamental concept in programming; every programming language has its own specific syntax that dictates how code should be written. When the code deviates from these rules, the compiler or interpreter cannot understand it, leading to a syntax error. This type of error prevents the program from compiling or being executed until it is fixed, as the code must adhere strictly to the defined syntax rules of the language.

In contrast, while other options may describe different types of errors or warnings, they do not accurately capture the essence of what a syntax error entails. For instance, potential logical errors refer to issues where the code runs successfully but does not produce the expected results, which is a different issue altogether. Missing semicolons might cause a syntax error in some languages, but they are just one specific example of many possible syntax violations. Lastly, runtime performance issues pertain to how the code operates during execution rather than its adherence to syntax. Thus, B clearly defines the critical aspect of syntax errors in programming.