---
title: "Effect basics"
description: "Effect keeps success values, expected failures, and required services in one computation model."
group: concept
terms:
  - "Effect basics"
  - "Effect computation"
sources:
  - https://youtu.be/gc5P36t6kD0?t=2955
  - https://youtu.be/und9h4xiIz4?t=752
---

# Effect basics

Michael describes an Effect through its output, predictable errors, and requirements. [Happy Path 81, 49:15](https://youtu.be/gc5P36t6kD0?t=2955).

He also describes a lazy Effect as a computation that can be transformed before it runs. [Why JavaScript Is Broken, 12:32](https://youtu.be/und9h4xiIz4?t=752).

See [context and requirements](/lore/context-and-requirements) and [the error model](/lore/error-model).