What types of HTTP headers are used to specify the data format transmitted in requests or responses?

Special headers are used to specify the data format transmitted in HTTP requests or responses:

• Content-Type: indicates the format of data in the request or response body. For example, application/json, text/html, application/xml.
• Accept: informs the server about the data formats the client is willing to accept in response.

Example of usage:

POST /api/data HTTP/1.1
Host: example.com
Content-Type: application/json
Accept: application/json

{"key":"value"}

Here, Content-Type: application/json indicates that the request body contains JSON, and Accept: application/json means the client expects to receive JSON in response.

These headers are important for proper data handling and serialization between the client and server.