C# delegates, Func, Action, events and lambdas explained

// ======================================================================
// Q: Delegates, Func, Action, events and lambdas?
//
// - Delegate: a type that represents a method (a type-safe function pointer).
//   Func<T, TResult> returns a value, Action<T> does not, Predicate<T> returns
//   bool.
// - Lambda: short syntax for a delegate or expression tree (x => x * 2). Lambdas
//   capture variables (closures), which costs an allocation.
// - Event: a delegate that only the owning class can invoke. Others can only +=
//   / -=. A forgotten -= on a long-lived publisher = memory leak.
// ======================================================================

Func<decimal, decimal> withVat = net => net * 1.24m;
Action<string> log = msg => Console.WriteLine(msg);
log($"Total: {withVat(100)}");