What is the header function used for in PHP?

The header function in PHP is primarily used to send raw HTTP headers to the client before any actual content is sent. This function allows developers to control many aspects of the HTTP response sent to the browser. By using the header function, PHP scripts can manipulate the HTTP protocol, affecting how the client (web browser) interprets the response.

For instance, when you want to send content-type headers (like Content-Type: text/html or Content-Type: application/json), the header function facilitates this. Additionally, it allows for setting various HTTP response status codes (like 200 for OK, 404 for Not Found, etc.) or configuring cache control directives. As such, it's a powerful tool that gives developers flexibility in shaping how responses are communicated to users and their browsers.

Although the options may include scenarios like redirection, cookie setting, or sending binary data, these functions are achieved using different specific methods or additional context surrounding the header function's capabilities. While it may seem that functions like header("Location: new_page.php") for redirection or setcookie() for cookies also relate, they represent specific applications of header manipulation rather than the direct overarching purpose of sending raw HTTP headers themselves.