Can you explain what the term 'critical section' means in parallel programming?

A critical section is a part of the code that must be executed by only one thread at a time to avoid conflicts when accessing shared resources (such as variables, files, devices). If multiple threads enter the critical section simultaneously without synchronization, it can lead to race conditions and errors.

To protect the critical section, synchronization mechanisms such as mutexes, semaphores, or language-specific constructs (for example, @synchronized in Objective-C) are typically used. This ensures that only one thread executes the code inside the critical section at any given time.