A Computer Network is a system of interconnected computers which use "communications media" to transmit data to each other.
Communications Media refer to the pathways, or methods, by which data are transmitted. Cable Media transmit information over physical wires or cables, whereas Broadcast Media (e.g. Bluetooth, WiFi, Cellular radio, Satellite radio) transmit information through electromagnetic waves.
The Internet is the most prevalent computer network in the world.
The most popular Internet architecture is called Client-Server. The Client is a computer which makes a request for information, whereas the Server provides a response to fulfill the client's request.
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The Internet primarily relies on the Hyper Text Transfer Protocol (HTTP), which specifies rules and standards for sending and receiving information.
According to HTTP, a client computer can issue different kinds of requests to the server. A client can either ask for data from the server (known as a GET request), or send some data to the server and ask the server to process it (e.g. POST and other types of request).
This course focuses exclusively on GET requests. The most common way a computer can issue a GET request is by visiting some URL in a browser. But a computer is also capable of programmatically issuing GET requests using command-line utilities and modern programming languages. Like other programming languages, VBA provides a way for the developer to write programs which issue HTTP requests.