Why Random generates different numbers in loop?

Hello there I want to generate random numbers, so I created method in my class

        private readonly Random _rand = new Random(); //Private property of class

        public void GenerateRandomNumber()
        {
            //For loop executes 10 times
            for (int i = 1; i < 11; i++)
            {
                Console.WriteLine(_rand.Next(0, 10));
            }
        }

When I call this from Main I create new instance of my class and then call it. It works properly but I want to know why does this generate different numbers each time in for loop and also each time I run the program?

That's interesting for me because I know that Random can generate same numbers but in my case it generates different ones.

How will it affect if I add static modifier to private property?