Wikipedia defines a Web Developer as:
a software developer or software engineer who is specifically engaged in the development of World Wide Web applications, or distributed network applications that are run over the HTTP protocol using an HTTP server, a web server, and an HTTP client, a web browser. Web developers can be webmasters who handle website administration and web design as well as web application development or can simply be web application developers. Web developers are formally in charge of web development within their respective organizations or also as freelance software developers.
So, do you want to become a web developer? I want this career as my sideline someday. Hehe. There are lots of opportunities in the World Wide Web and I want to take advantage of these opportunities.