# Observables and RxJS Basics

An observable is a stream of values that arrive over time. Nothing happens until you subscribe, with handlers for the values, an error and the end. HttpClient's observables send one value, the response, then complete. RxJS operators in pipe, such as map, transform the values.

![Cheat sheet: Observables and RxJS Basics](https://fsdtrainingmedia.blob.core.windows.net/public/images/2026/11/a6766a217cde4318a966b42534462ea2.webp)

- Category: Angular
- Level: Journeyman
- Tags: angular, Observable, RxJS, RxJS Operators, subscribe()
- Updated: November 3, 2026

Source: https://www.ask-codey.com/cheat-sheets/calling-apis-from-angular-observables-and-rxjs-basics-cheat-sheet