What are lambda expressions in C#?

A lambda expression is an anonymous function that can be used to create delegates or expression trees. It provides a more concise syntax for writing inline methods.

Example:

// Lambda expression that takes one parameter and returns its square
Func<int, int> square = x => x * x;
int result = square(5); // result = 25

// Lambda expression with no parameters
Action greeting = () => Console.WriteLine("Hello!");
greeting(); // Outputs "Hello!"

// Lambda expression with multiple parameters
Func<int, int, int> add = (a, b) => a + b;
int sum = add(3, 7); // sum = 10