- [Instructor] Hypertext Transfer Protocol or HTTP
is heavily used on the internet for standard web browsing.
HTTP traditionally runs on TCP port 80.
The ports can be changed for security or testing purposes,
but all browsers will natively attempt
to connect on port 80.
HTTP is a plaintext protocol
designed to transfer a hypertext.
Its first RFC was ratified in 1997.
HTTP functions in a client/server
request and response method.
Generally, a client opens a browser
and makes an HTTP request to a web server.
The server will comply by providing whatever resources
were requested, be it HTML, an image, and so on.
Any application that accesses web content in any way
is called a user agent.
This could be a browser, a mobile app,
or a search engine indexing service.
HTTP resources are located
via Uniform Resource Locators or URLs.
When requesting resources, a single connection can be used
to transfer images, scripts, et cetera,
which causes less latency for the transfer overall.
HTTP provides several challenge response mechanisms
to provide authentication.
It can also employ authentication realms.
This allows an authenticated user
access to various authentication scopes
under a single URL root.
HTTP has several request methods
that will perform different actions on the web server.
The get method is used to retrieve data.
The head method is identical to get,
but doesn't include the response body.
The post method accepts some action
or information from the client.
This would be submitting a form
or creating a post on a forum.
The first line of an HTTP response
is known as the status line
and includes a numbered status code
and a text-based reason phrase.
This could be something like Status 404: Reason not found.
They come in five flavors:
informational, successful, redirection, client error,
and server error.
HTTP/2 was first published as RFC 7540 in 2015.
In 2021, more than 50% of the top 10 million websites
support the protocol
and most major web browsers supported the protocol
by the end of 2015.
The protocol has backwards compatibility with HTTP/1.1
and decreases latency via several optimizations
and new techniques.
HTTP/3 became an internet draft in 2021
with default support in many major web browsers as of 2020.
HTTP/3 switches to the transport layer
network protocol quick,
which does delivery over UDP instead of TCP
to provide even more efficiencies.
HTTP is a core component of any internet connection.
And with the rise of hosted browser-based services,
it has become essential.