Error "No provider for HttpClient" in Angular: causes and fix

Hi! I'm new to Angular and TypeScript. I'm trying to make an HTTP request to an API in my application, but when I run it I get the error: ``` NullInjectorError: No provider for HttpClient! ``` Here's my code. The `DataService` service: ```typescript import { Injectable } from '@angular/core'; import { HttpClient } from '@angular/common/http'; @Injectable() export class DataService { constructor(private http: HttpClient) {} getPosts() { return this.http.get('https://jsonplaceholder.typicode.com/posts'); } } ``` The `AppComponent` component: ```typescript import { Component, OnInit } from '@angular/core'; import { DataService } from './data.service'; @Component({ selector: 'app-root', template: '' }) export