Properties

A property looks like a field from the outside but is backed by get/set accessors — C#'s built-in way to do what Java does with a manual getBalance()/setBalance() pair, but with field-like syntax at the call site.

class BankAccount {
    private double _balance;

    public double Balance {
        get => _balance;
        set {
            if (value < 0) {
                throw new ArgumentException("Balance cannot be negative");
            }
            _balance = value;
        }
    }
}

var account = new BankAccount();
account.Balance = 100;       // calls the setter
Console.WriteLine(account.Balance); // calls the getter — 100

An auto-property skips the backing field entirely when there's no extra logic:

public int Age { get; set; }             // fully open
public int Id { get; private set; }       // read-only from outside

Common mistakes

• Writing a plain public field where a property (even a simple auto-property) would be more idiomatic — properties let you add validation later without breaking every caller's syntax.