What is a "stack overflow"?

A stack overflow occurs when a program uses more stack memory than is allocated, leading to the exhaustion of the space reserved for the stack. Each time a function is called, a new frame is added to the stack, which contains information like local variables and the return address. If a program has many nested function calls or infinite recursion, it can quickly consume the available stack space, resulting in a stack overflow error. This typically leads to a crash or abnormal termination of the program.

The other options do not correctly define a stack overflow. For example, while performance optimization techniques exist, they typically involve different concepts like algorithm efficiency rather than issues with stack size. Similarly, data storage methods in cloud computing and algorithms for sorting arrays refer to entirely different areas of computer science, unrelated to the specific issue of stack memory management.