A web client accesses a web application using what protocol?

TCP is the transport-layer protocol that carries HTTP traffic, but web clients do not directly interact with TCP as the application protocol - HTTP sits above TCP in the OSI model.

XML is a data serialization and markup language used to structure data, not a communication protocol for transmitting requests between clients and servers.

HTML is a markup language used to structure and display web page content, not a protocol - it is the payload carried by HTTP, not the communication mechanism itself.

HTTP is the application-layer protocol that defines how web clients (browsers) format and transmit requests to web servers, and how servers respond. It operates over TCP at the transport layer and is the foundational protocol of the World Wide Web, enabling retrieval of HTML pages, images, and other web resources.