# What is the use of useEffect React Hooks?

The Effect Hook lets you perform side effects in function components. Data fetching, setting up a subscription, and manually changing the DOM in React components are all examples of side effects. 

**Effects Without Cleanup**
Sometimes, we want to run some additional code after React has updated the DOM. Network requests, manual DOM mutations, and logging are common examples of effects that don’t require a cleanup.

**Effects with Cleanup**
We might want to set up a subscription to some external data source. In that case, it is important to clean up so that we don’t introduce a memory leak! 

Sources:

Using the Effect Hook –. (n.d.). React. https://reactjs.org/docs/hooks-effect.html