How is data transferred to an external site using HTTP?

Data is transferred to an external site using HTTP (Hypertext Transfer Protocol) primarily through a request made via a TCP (Transmission Control Protocol) connection. HTTP operates on top of the TCP layer of the internet protocol suite, which establishes a connection between a client (such as a web browser) and a server. When a user requests a webpage or a resource from a server, the web browser uses TCP to send that request over the internet. This connection ensures that the data packets sent between the client and server are delivered reliably and in the correct order.

By using TCP, the HTTP protocol guarantees the integrity of the data transfer, making it the backbone of web communication. The client initiates the connection, and the server responds accordingly, transferring the requested data efficiently over the established TCP connection. This mechanism is foundational to how web browsing and data retrieval function on the internet.