Let's take a closer look at this query here to see what parts it consists of:

query PersonQuery { 
  person(id: "cGVvcGxlOjE=") { 
    name, 
    gender, 
    homeworld { 
      name 
    } 
  } 
} 

The first line defines an operation named PersonQuery that queries data from the server, where the query keyword is one of the three currently supported operations: query, mutation, and subscription.

Specifying the query keyword and an operation name (PersonQuery in this case) is only required when a GraphQL document defines multiple operations. We, therefore, could have written the previous query with a shorthand version:

{ 
  person(id: "cGVvcGxlOjE=") { 
    name, 
    gender, 
    homeworld { 
      name 
    } 
  } 
} 

The person, name, and homeworld keywords are all query fields, where name and gender fields are considered to be leaf nodes of the query, requesting scalar values such as strings, Boolean values, and numbers; and person and homeworld are the fields that correspond...