What is a buffer overflow in programming?

A buffer overflow is indeed a programming error related to memory. It occurs when a program writes more data to a block of memory, or buffer, than it was allocated for. This overflow can lead to unexpected behavior in the application, including data corruption, crashes, or vulnerabilities that could be exploited by attackers.

When a buffer overflow happens, the excess data can overwrite adjacent memory locations, potentially altering the control flow of the program. This can allow malicious users to execute harmful code or gain unauthorized access to a system, which is why understanding buffer overflows is crucial for software development and security practices.

The other options do not accurately describe a buffer overflow. It is not a security feature or a method for optimizing performance, nor is it primarily a data storage technique. Instead, it is a mistake in managing memory that can lead to significant security risks if not properly handled.