I dont understand the difference between:

@future (callout= true)

and

@future (callout= false)

Here is the documentation, but I don't understand where to use one or the orther: https://developer.salesforce.com/docs/atlas.en-us.apexcode.meta/apexcode/apex_classes_annotation_future.htm

I don't understand the difference between:

@future (callout= true)

and

@future (callout= false)

I have read the documentation, but I don't understand where to use one or the other.