# Introduction to ZSink

> A `ZSink[R, E, I, L, Z]` is used to consume elements produced by a [`ZStream`](../zstream/index.md). You can think of a sink as a function that will consume a variable amount of `I` elements (could be 0, 1, or many!), might fail with an error of type `E`, and will eventually yield a value of type `Z` together with a remainder of type `L` as [leftover](leftovers.md).

A `ZSink[R, E, I, L, Z]` is used to consume elements produced by a [`ZStream`](../zstream/index.md). You can think of a sink as a function that will consume a variable amount of `I` elements (could be 0, 1, or many!), might fail with an error of type `E`, and will eventually yield a value of type `Z` together with a remainder of type `L` as [leftover](leftovers.md).

To consume a stream using `ZSink` we can pass `ZSink` to the `ZStream#run` function:

```scala

val stream = ZStream.fromIterable(1 to 1000)
val sink   = ZSink.sum[Int]
val sum    = stream.run(sink)
```

`ZSink` has one type alias called `Sink`. `Sink[E, A, L, B]` is a type alias for `ZSink[Any, E, A, L, B]`. We can think of a `Sink` as a function that does not require any services and will consume a variable amount of `A` elements (could be 0, 1, or many!), might fail with an error of type `E`, and will eventually yield a value of type `B`. The `L` is the type of elements in the leftover.

```scala
type Sink[+E, A, +L, +B] = ZSink[Any, E, A, L, B]
```

## See Also

- [ZSink](concurrency-and-parallelism.md) — Describes concurrent and parallel operations with multiple sinks.
- [Creating Sinks](creating-sinks.md) — Explains how to create ZSink instances
- [Sink Operations](operations.md) — Describes how to transform and operate on sinks