-d in curl means code example
Example: -d in curl request
curl --request POST \
--url https://api.sendgrid.com/v3/mail/send \
--header 'Authorization: Bearer YOUR_API_KEY' \
--header 'Content-Type: application/json' \
--data '{"personalizations": [{"to": [{"email": "[email protected]"}]}],"from": {"email": "[email protected]"},"subject": "Hello, World!","content": [{"type": "text/plain", "value": "Heya!"}]}'