What are Angular Interceptors and how do you implement them?

HTTP Interceptors intercept and modify HTTP requests/responses. Implement HttpInterceptor interface: @Injectable() export class AuthInterceptor implements HttpInterceptor { intercept(req: HttpRequest, next: HttpHandler): Observable> { const authReq = req.clone({ setHeaders: { Authorization: "Bearer " + token } }); return next.handle(authReq); } }