The whole architecture of the Web is based on the client-server, request-response protocol of HTTP. This colors everything that you do when you create interactive web pages.
Web browsers come in many flavors from many companies (or open source programming groups) and each has its own idiosyncrasies. Here, I'll stick to the basics, and the code should display okay on any standard web browser.
As you go forward, keep in mind the problem of incompatibility among web browsers and realize that at some point, it may become necessary for you to deal with the problem in the code you write for the Web.