http header are the field in http api request and response.

it is like setting up the address from and to in sending envelop to postman.

similarly http header are doing so.
*simple request header *

response header for same request

** some of build in header are **

• host
• path
• content-type and many other refer doc

_u can add own custom header. _
like req.setHeader("X-myname","sallbro");
it is best practise to add X before name of header to identify it is custom header.