7 ways to start a Task in .NET C#
https://dotnetcodr.com/2014/01/01/5-ways-to-start-a-task-in-net-c/

New threads can be started using the Task Programming Library in .NET in – at last – 5 different ways.

C# 5種啟動 Task 的方法

You’ll first need to add the following using statement:
using System.Threading.Tasks;

1. The most direct way
Task.Factory.StartNew(() => {Console.WriteLine("Hello Task library!"); });


2. Using Action
Task task = new Task(new Action(PrintMessage));
task.Start();

…where PrintMessage is a method:
private void PrintMessage()
{
    Console.WriteLine("Hello Task library!");
}

3. Using a delegate
Task task = new Task(delegate { PrintMessage(); });
task.Start();
Lambda and named method

Task task = new Task( () => PrintMessage() );
task.Start();


4. Lambda and anonymous method

Task task = new Task( () => { PrintMessage(); } );
task.Start();

Using Task.Run in .NET 4.5
public async Task DoWork()
{
    await Task.Run(() => PrintMessage());
}

5. Using Task.FromResult in .NET4.5 to return a result from a Task
public async Task DoWork()
{
    int res = await Task.FromResult<int>(GetSum(4, 5));   
}
 
private int GetSum(int a, int b)
{
    return a + b;
}

You cannot start a task that has already completed. 
If you need to run the same task you’ll need to initialise it again.