Word
GraphQL
GraphQL is one way a program asks an API a question, where the question spells out exactly which fields you want back.
Also called: graph query language
Older styles of API hand you a fixed bundle: here is the whole order, sort it out yourself. With GraphQL you write a short request saying order number, customer email, tracking number, and that is what comes back, nothing else, and fewer round trips.
Your store's API may well work this way, and your agent writes these requests for you; you do not need the syntax. What you do need to know: asking for more fields is never free, and when something comes back missing, the usual cause is that nobody asked for it.