[2] The IETF HTTP working group found that the most popular web browsers tolerate the passing of a relative URL[3] and, consequently, the updated HTTP 1.1 specifications (IETF RFC 7231) relaxed the original constraint, allowing the use of relative URLs in Location headers.
For example, the HTTP scheme-specific syntax and semantics for HTTP URLs requires a "host" (web server address) and "absolute path", with optional components of "port" and "query".
In order to be understood they must be combined with the URL of the original request.
A client request for https://www.example.com/blog/all may get a server response with a path that is absolute because it starts with a slash:[7] The URL of the location is expanded by the client to https://www.example.com/articles/.
[8] A client request for https://www.example.com/blog/latest may get a server response with a path that is relative because it doesn't start with a slash:[7] The client removes the path segment after the last slash of the original URL and appends the relative path resulting in https://www.example.com/blog/2020/zoo.