 Kai, let's talk about interfaces in TypeScript, first let's make a new file, let's save it as interfaces.ts, interfaces in TypeScript are a way of representing complex types for any object, also we could say that interfaces define a set of properties, methods and events, but they do not provide their implementation, so in interfaces we don't have implementation, so inside one interface you can have properties, methods, events and you don't need to provide their implementation. Okay, also we could say that interfaces are some kind of types that contain a list of members, let's say that we will have member 1, member 2 and so on. Okay, let's make an interface that represents object that have for example username and password field, so we're going to make interface user and we will provide its list of members, for example let's make first member username, that username will be string type and let's make for example password which will also be a string, a lot of programmers also like when they're working with an interface to use in front of its name letter I, capital letter I which will suggest to other programmers that this name represents an interface, so it will be easier to work and maintain your code, also we could also say that we can have an interface in TypeScript, but after compilation to JavaScript interface will not exist anymore, so interfaces are defined just in TypeScript and we don't have them in JavaScript. Okay, that's all for now about interfaces in TypeScript, see you in the next video, bye bye.