System.Threading.Timer - Simplest multithreaded timer. Contains two methods and one constructor.

Example: A timer calls the DataWrite method, which writes “multithread executed…” after five seconds have elapsed, and then every second after that until the user presses Enter:

using System;
using System.Threading;
class Program
{
  static void Main()
  {
    // First interval = 5000ms; subsequent intervals = 1000ms
    Timer timer = new Timer (DataWrite, "multithread executed...", 5000, 1000);
    Console.ReadLine();
    timer.Dispose(); // This both stops the timer and cleans up.
  }

  static void DataWrite (object data)
  {
    // This runs on a pooled thread
    Console.WriteLine (data); // Writes "multithread executed..."
  }
}

Note : Will post a separate section for disposing multithreaded timers.

Change - This method can be called when you would like change the timer interval.

Timeout.Infinite - If you want to fire just once. Specify this in the last argument of the constructor.

System.Timers - Another timer class provided by .NET Framework. It wraps the System.Threading.Timer.

Features:

• IComponent - Allowing it to be sited in the Visual Studio’s Designer’s component tray
• Interval property instead of a Change method
• Elapsed event instead of a callback delegate
• Enabled property to start and stop the timer (default value = false)
• Start & Stop methods in case if you get confused by Enabled property (above point)
• AutoReset - for indicating a recurring event (default value = true)
• SynchronizingObject property with Invoke and BeginInvoke methods for safely calling methods on WPF elements and Windows Forms controls

Example representing all the above features:

using System;
using System.Timers; // Timers namespace rather than Threading
class SystemTimer
{
  static void Main()
  {
    Timer timer = new Timer(); // Doesn't require any args
    timer.Interval = 500;
    timer.Elapsed += timer_Elapsed; // Uses an event instead of a delegate
    timer.Start(); // Start the timer
    Console.ReadLine();
    timer.Stop(); // Stop the timer
    Console.ReadLine();
    timer.Start(); // Restart the timer
    Console.ReadLine();
    timer.Dispose(); // Permanently stop the timer
 }

 static void timer_Elapsed(object sender, EventArgs e)
 {
   Console.WriteLine ("Tick");
 }
}

Multithreaded timers - use the thread pool to allow a few threads to serve many timers. It means that callback method or Elapsed event may trigger on a different thread each time it is called.

Elapsed - this event always fires on time—regardless of whether the previous Elapsed event finished executing. Because of this, callbacks or event handlers must be thread-safe. The accuracy of multithreaded timers depends on the OS, and is typically in the 10–20 ms.

interop - when ever you need greater accuracy use this and call the Windows multimedia timer. This has accuracy down to 1 ms and it is defined in winmm.dll.