 Hi, in this lesson, we're going to talk a little bit about interaction between interfaces and classes in TypeScript. Also, we're going to talk about that, how to implement interface in TypeScript. First, let's make an interface. For example, let's say interface user. And let's provide few things that our interface will keep together. Let's make, for example, variable username. Username is going to be string and let's make variable password, which will also be a string. And let's put inside our interface a method. Let's call it, for example, add user and let's put as arguments username, which will be string and password. Which will also be a string and our function will not return anything. When you're making interfaces, you can start the name of your interface with first letter I, which will suggest to you further in your code and to your colleagues, programmers that these names represents an interface. Currently, we don't have the implementation for our interface. So we could, for example, make a class. How to call it? Let's call it, for example, account. And we want to implement our interface with this class. So we're going to use keyword implements and we're going to add after keyword implements our interface. We can also create a lot of other interfaces and add them to this list. So our class class account can implement a lot of interfaces. But in this example, we're going to create implementation of just one interface. In this class, we need to implement our add user method and we can use these variables. So I'll use this variable username, which will be string and I will make it public. So it will be visible. Same, I will make public string variable, excuse me, password variable, which is going to be string and then we need to implement our method. Let's make it again public or maybe private. I don't know. Private method add user and we're going to provide arguments. Username is going to be string and password is going to be string. Then we want to assign our username and password arguments to our public variables. We're going to use this keyword. So this username, that means this variable will have the value of this argument username and also string password is going to have this value, which is giving to our function by this password argument. Okay, that's it. I can just provide, for example, but there is no need to do that. For example, to implement a constructor, but I don't know. Maybe we will do it in some other video. Let's say maybe password to be string, but TypeScript compiler can provide to us by default and constructor, so I will delete it. That's all in this lesson. Please like this video, share it, please subscribe to my channel. That's all for now. See you in the next lesson. Bye.