What data is usually added to headers when sending an HTTP request?

HTTP request headers typically carry metadata that helps the server understand the request context and process it correctly. Main data types in headers:

• Authorization information: tokens, keys, cookies (e.g., Authorization: Bearer <token>).
• Content-Type: indicates the format of the request body (Content-Type: application/json).
• Accept: specifies the format in which the client wants to receive the response (Accept: application/json).
• Client information: User-Agent, language (Accept-Language), cookies.
• Caching: headers controlling caching (If-Modified-Since, Cache-Control).
• Others: headers for connection management (Connection), body length (Content-Length), referrer (Referer).

Example in Go:

req, _ := http.NewRequest("GET", "https://example.com", nil)
req.Header.Set("Authorization", "Bearer mytoken")
req.Header.Set("Accept", "application/json")
req.Header.Set("User-Agent", "MyClient/1.0")