How does semaphore.CurrentCount work in this context?

Question

I just started learning SemaphoreSlim but how does the semaphore.CurrentCount increments and decrements in this program? From my understanding, when semaphore.Wait() is called the release counter is decremented by 1 and when semaphore.Release(), two threads are allowed to execute but how does the semaphore.CurrentCount get incremented? does it start from 0 or 1 ?

        var semaphore = new SemaphoreSlim(2, 10);
        for (int i = 0; i < 20; i++)
        {
            Task.Factory.StartNew(() =>
            {
                Console.WriteLine("Entering task " + Task.CurrentId);
                semaphore.Wait(); //releasecount--
                Console.WriteLine("Processing task " + Task.CurrentId);
            });
        }

        while (semaphore.CurrentCount <= 2)
        {
            Console.WriteLine("Semaphore count: " + semaphore.CurrentCount);
            Console.ReadKey();
            semaphore.Release(2);
        }
        Console.ReadKey();

Answer 1

Wait decrements it and Release increments it.

Answer 2

The semaphore is like a room with a certain capacity. With SemaphoreSlim you are specifying the initial capacity and the maximum. After it reach the maximum, no one can enter anymore to the room. Per every item that leaves the room, only one is allowed to enter.

The CurrentCount gets the number of remaining threads that can enter the room.

    for (int i = 0; i < 20; i++)
    {
        Task.Factory.StartNew(() =>
        {
            Console.WriteLine("Entering task " + Task.CurrentId);
            semaphore.Wait(); //only from 2 - 10 threads can be at the time
            Console.WriteLine("Processing task " + Task.CurrentId);
        });
    }

And here

while (semaphore.CurrentCount <= 2) 

if at that moment the number of remaining threads is less than 2 then you are releasing two spaces on the room