Parameters: optional, named, overloaded
Defaults callers can skip, named arguments for clarity, and overloads that adapt one name to several shapes.
Optional parameters
static void Log(string message, int level = 1)
{
Console.WriteLine("[" + level + "] " + message);
}
Log("boot"); // [1] boot — level omitted, default used
Log("disk full", 3); // [3] disk full
A default value makes the trailing parameter skippable. Rules: optional parameters come after required ones, and the default must be a compile-time constant. Defaults are baked into the caller's compiled code — changing a default later requires recompiling callers. That's a real library-design consequence; for now, just know defaults are convenient for self-contained code.
Named arguments
Log(level: 3, message: "disk full"); // same call, order-free
Log("disk full", level: 3); // positional then named
Named arguments say what each value is at the call site. They also let you skip middle optional parameters instead of passing them all positionally. Use them when a call would otherwise carry bare numbers or bools whose meaning isn't obvious at a glance: Resize(img, width: 800) beats Resize(img, 800).
Overloading: one name, several signatures
static int Max(int a, int b) => a > b ? a : b;
static double Max(double a, double b) => a > b ? a : b;
static int Max(int[] values) { /* scan */ }
Three methods, one concept, one name. The compiler picks the overload whose parameter types match the arguments (or the best implicit conversion). Overloads must differ in their parameter lists — a different return type alone is a compile error (CS0111). Overload when the concept is identical and only the input shape differs; if the behavior meaningfully changes, a distinct name is more honest.