contentType web code example

Example 1: content-type header api

Content-Type header is used in POST , PUT , PATCH to
specify the type of body you are sending 
to the serve and it's required.

Example 2: mime type

media type is a two-part identifier to file formats and format contents 
transmitted on the Internet. The Internet Assigned Numbers Authority is 
the official authority of the standardization and publication of these 
classifications. 
also almost of an old extension on the internet is MIME type.