Why? We do this to make it easier to tell the difference between what is a class or method, and what is a variable. Also, Microsoft suggests beginning method names with an uppercase letter. If someone else ever looks at your code, they will expect to see method names beginning with an uppercase letter.

Using this example again:

void AddTwoNumbers ()
{
  // Code goes here
}

You can see the name is actually three words squished together. Since method names can only one word, the first word begins uppercase, then just capitalize the first letter of each additional word. For example, PascalCasing.

The method name always includes a pair of parentheses on the end. The parentheses not only let you know that the name is a method, but they do serve an important purpose of allowing you to input some data into the method when needed.