Explain what an NSThread object is and how it is used to manage threads in iOS or macOS applications.

NSThread is a class in iOS and macOS that represents a separate thread of execution. It allows creating and managing threads at a low level.

With NSThread, you can:

• Create a new thread in which specific code will be executed.
• Start, pause, and terminate threads.
• Pass data between threads.

Example of creating and starting a thread using NSThread:

NSThread *thread = [[NSThread alloc] initWithBlock:^{
    // Code to be executed in the new thread
    NSLog(@"Thread started");
}];
[thread start];

However, in modern applications, higher-level APIs such as GCD (dispatch_async) or OperationQueue are more commonly used, as they are simpler and safer to use.