properties.cs

    public class Money
    {
        public decimal Amount { get; private set; } = 20m;
        
        public void doStuff()
        {
            Amount *= 2;
        }
    }
    
    
    public class ImmutableMoney
    {
        public decimal Amount { get; } // no set accessor!; 
        
        public ImmutableMoney(decimal amount)
        {
            Amount = amount;
        }
        
        public void doStuff()
        {
            // error CS0200: Property (...)) cannot be assigned to -- it is read only
            // Amount *= 2; <- impossible
        }
    }
    
    
    public class Program
    {
        static void Main()
        {
            var money = new Money();
            money.doStuff();
            Console.WriteLine(money.Amount);
            
            var immutable = new ImmutableMoney(10m);
            Console.WriteLine(immutable.Amount);
        }
    }