Understand the basics of Vue.JS?

Question

Vue.js

I'm learning JS and Vue.JS and I've come across the fact that I don't understand the basics of Vue and reading the documentation does not clarify them.
vuejs.org/api/#data
With the creation of the Vue object, everything seems to be clear. However, what does `data` mean?

As I understand it, you can call an extended constructor called Vue.extend. You can create a component in it. But why is it necessary to return when it is called from a component?
"When defining a component, data must be declared as a function that returns the initial data object, because there will be many instances created using the same definition".

If I do a basic version that is not a return component, then what will happen?

What does `methods` mean? What should I put in there? Can I call functions in `data`?

Answer 1

data is a model, an object where all application data will be
methods - data processing functions, application logic,
roughly speaking, functions from methods process the data model and blocks subscribed to data from the model dynamically change in templates