Understanding basic GraphQL Schema

It's my first post on DEV. Also, I'm not an expert in GraphQL, I'm just learning it, so...

Goal: understand how GraphQL Schema is working.

I've decided to rebuild my portfolio website with Gatsby. So I started to learn from Gatsby Tutorial how to work with Gatsby. In tutorial-part-four, reading about data in Gatsby, I move to [howtographql tutorial] cause I've had no experience with GraphQL before. If you check out basic core concept for GraphQL you can see an example of Schema Definition:

type Query {
  allPersons(last: Int): [Person!]!
}

type Mutation {
  createPerson(name: String!, age: Int!): Person!
}

type Subscription {
  newPerson: Person!
}

type Person {
  name: String!
  age: Int!
  posts: [Post!]!
}

type Post {
  title: String!
  author: Person!
}

Trying to understand, how it works I write short syllabus about core concepts from full article for myself in Russian.

And also I've created picture for visual perception. Hope, it'll help somebody.