Using curl with GraphQL server

I have just started playing around with GraphQL and I just wanted to find out how you could use curl for testing GraphQL APIs.

curl 'https://countries.trevorblades.com/' \
  -X POST \
  -H 'content-type: application/json' \
  --data '{ "query": "{ continents { code name } }" }'

Resources and References

1. Blog post by Max Ivanov
2. GitHub example
3. Example GraphQL APIs