dioxus/docs/guide/src/interactivity/lifecycles.md

Effects

In theory, your UI code should be side-effect free. Whenever a component renders, all of its state should be prepared ahead of time. In reality, we often need to perform some sort of side effect. Possible effects include:

• Logging some data
• Pre-fetching some data
• Attaching code to native elements
• Cleaning up

This section is organized under interactivity because effects can be important to add things like transitions, videos, and other important media.