 Hi, in this lesson, we're going to talk about typeguards. First, let's make a variable, let's call it my variable and let's say that our variable will have any type. Now we want to check if our variable at some point of time can be a string or maybe number or some other basic or complex type in TypeScript. We can do that by using if statement and inside our if statement we're going to ask if our variable is type of string. Inside this statement, we're going to use three equal signs to check if this is true and this is known as type guard and means that the type of my variable will be treated as a string inside this if statements block. So inside our if statements block after checking that our variable is a string, the same variable will be treated as a string. So we could say for example that my variable is equal to a new string, which will be for example this is a string, this is a string, okay? Similarly to that, we can define another if statement with similar checking if our variable is now a number and if our variable is now a number inside this if code block it will be treated as an integer. So as a number, this is known as type guard. So let's say that our variable is now treated as a number. So we could assign to our variable value one. So in your code, you will have situations when your variable will not be the variable of any type, but it can be a variable of the union of types. For example, your variable can be the union of string or number or Boolean type and so on here I'm pointing just simple types. You can use the union of some complex types, but it doesn't matter for now and for this video and this lesson. So in this lesson, we talked about type guard and that means that our variable was treated as a string in this code block or a number in this code block. That's all in this lesson. Thanks for watching. See you in the next video.