# RxJS Observables — Angular

Source: https://www.geekswithgeeks.com/en/angular/ng-rxjs-observables

> Streams of values over time, and how to work with them.

## What's an Observable?

An **Observable** represents a stream of values delivered over time — an HTTP response, a click stream, or route changes are all Observables in Angular.

## subscribe()

Nothing runs until you `subscribe`. The callback receives each emitted value.

```typescript
this.productService.getProducts().subscribe(products => {
  this.products = products;
});
```

## Operators: map & filter

`pipe()` chains operators to transform the stream — `map` reshapes values, `filter` drops ones you don't want.

```typescript
this.productService.getProducts().pipe(
  map(products => products.filter(p => p.inStock)),
).subscribe(inStockProducts => {
  this.products = inStockProducts;
});
```

## The async pipe

In the template, `| async` subscribes for you and unsubscribes automatically — no manual cleanup needed for that binding.