The forms of lambda expressions

x=>x*x;//A simple expression that returns the square of its parameter. The type of parameter x is inferred from the context.
x=>{return x*x;};// Semantically the same as the preceding. expression, but using a c# statement block as a body rather than a simple expression.
(int x)=>x/2;//A simple expression that returns the value of the parameter divided by 2. The type of parameter x is stated explicitly.
()=>folder.StopFolding(0);//Calling a method. The expression takes no parameters. The expression might or might not return a value.
(x,y)=>{x++;return x/y;}//Multiple parameters; the compiler infers the parameter types. The parameter x is passed by value. so the effect of the ++ operation is local to the expression.
(ref int x,int y)=>{x++;return x/y;}//Multiple parameters with explicit types Parameter x is passed by reference, so the effect of the ++ operation is permanent.

If a lambda expression takes parameters, you specify them in the parentheses to the left of the => operator. You can omit the types of parameters, and the c# compiler will infer their types from the context of the lambda expression. Yor can pass parameters by reference(by using the ref keyword)if you want the lambda expression to be able to change its values other than locally, but this is not recommended.
Lambda expressions can return values, but the return type must match that of the delegate to which thye are being added.
The body of a lambda expression can be a simple expression or a block of c# code made up of multiple statements, method calls, variable definitions, and other code items.
Variables defined in a lambda expression method go out of scope when the method finishes.
A lambda expression can access and modify all variables outside the lambda expression that are in scope when the lambda expression is defined. Bevery carful with this feature!