What does the "http" at the start of a web address stand for?

HTTP stands for HyperText Transfer Protocol, the standardized set of rules that govern how web browsers and servers communicate when requesting and sending web pages, images, and other content across the internet. It defines how a browser asks for a page and how a server structures its response, forming the basic language underlying almost all ordinary web browsing.

The other options are not real expansions of the acronym, they simply resemble technical-sounding phrases without corresponding to the actual established meaning behind HTTP, which references hypertext, the linked documents the web was originally built around, and the protocol used to move them.

Adding an 's' to make HTTPS layers encryption on top of this same basic protocol, scrambling the data exchanged between browser and server so that outside parties intercepting the connection cannot easily read sensitive information like passwords or payment details as they travel across the network.