# HTTPS:// URLs HTTP/3 will be performed using `HTTPS://` URLs. The world is full of these URLs and it has been deemed impractical and downright unreasonable to introduce another URL scheme for the new protocol. Much like HTTP/2 did not need a new scheme, neither will HTTP/3. The added complexity in the HTTP/3 situation is however that where HTTP/2 was a completely new way of transporting HTTP over the wire, it was still based on TLS and TCP like HTTP/1 was. The fact that HTTP/3 is done over QUIC changes things in a few important aspects. Legacy, clear-text, `HTTP://` URLs will be left as-is and as we proceed further into a future with more secure transfers they will probably become less and less frequently used. Requests to such URLs will simply not be upgraded to use HTTP/3. In reality they rarely upgrade to HTTP/2 either, but for other reasons. ## Initial connection The first connection to a fresh, not previously visited host for a HTTPS:// URL probably has to be done over TCP (possibly in addition to a parallel attempt to connect via QUIC). The host might be a legacy server without QUIC support or there might be a middle box in between setting up obstacles preventing a QUIC connection from succeeding. A modern client and server would presumably negotiate HTTP/2 in the first handshake. When the connection has been setup and the server responds to a client HTTP request, the server can tell the client about its support of and preference for HTTP/3. --- # Agent Instructions: Querying This Documentation If you need additional information that is not directly available in this page, you can query the documentation dynamically by asking a question. Perform an HTTP GET request on the current page URL with the `ask` query parameter: ``` GET https://http3-explained.haxx.se/en/h3/h3-https.md?ask= ``` The question should be specific, self-contained, and written in natural language. The response will contain a direct answer to the question and relevant excerpts and sources from the documentation. Use this mechanism when the answer is not explicitly present in the current page, you need clarification or additional context, or you want to retrieve related documentation sections.