ThreadPoolExample.cs

using System;
using System.Threading;

public class ThreadPoolExample
{
    public static void Main()
    {
        // Queue a task.
        ThreadPool.QueueUserWorkItem(DoWork, "Task 1");

        // Queue another task.
        ThreadPool.QueueUserWorkItem(DoWork, "Task 2");

        // Wait for user input before exiting.
        Console.ReadLine();
    }

    // This method will be executed by a thread from the thread pool.
    public static void DoWork(object state)
    {
        Console.WriteLine($"Executing {state} on thread {Thread.CurrentThread.ManagedThreadId}");
        Thread.Sleep(2000); // Simulate some work.
        Console.WriteLine($"{state} completed.");
    }
}