Properties and methods are important concepts in object-oriented programming. They enable us to encapsulate data and behavior within objects.

Properties

Properties in C# are members of a class and are used to get or set values. They offer a way to protect a field in a class by reading or writing to it through the property, providing a layer of security and validation.

public class Person
{
    // A private field, typically this is where data is stored
    private string name;

    // A public property, used to control access to the private field
    public string Name
    {
        get { return name; }
        set { name = value; }
    }
}

In the above example, Name is a property. It provides a way to read or write to the name field.

You can also have read-only properties or write-only properties by only providing either the get or set accessor, respectively. In C# 6 and later, you can initialize auto-implemented properties directly from their declaration, simplifying your code:

public class Person
{
    // Auto-implemented properties for trivial get and set
    public string Name { get; set; }
    public int Age { get; set; } = 18; // With initializer
}

Methods

Methods in C# are operations that objects can perform. They are defined within a class or struct and typically operate on data that is contained in the class.

public class Calculator
{
    public int Add(int a, int b)
    {
        return a + b;
    }
}

In this example, Add is a method that takes two parameters and returns their sum.

You can create an instance of the Calculator class and call its Add method like this:

Calculator calculator = new Calculator();
int sum = calculator.Add(1, 2);  // sum is 3

Note: Methods can have any number of parameters (including zero), and they can return a value or be void (returning no value).