Since HTML alone provides only a crude level of interactivity (namely links, form elements, buttons and image maps), Java Script was developed.
Although it would be helpful, I do assume that you have prior experience in computer programming beyond hand-coding in HTML.
Web applications are by nature distributed applications.
When the web server receives a request for a file with a name ending in .php, it opens and searches the file until it encounters the PHP start tag ".
Just as a jar can hold pickles, a variable holds data like numbers or text.
Java Script code is often contained within an HTML file enclosed by the tag. The web server is fully ignorant about Java Script (well, there is something like server-side Java Script but let's not talk about it); it just serves up any HTML, Java Script or pictures that have been requested without analysing or executing any code.
To further avoid confusion: Beyond its name, Java Script has very little in common with Java, which is a programming language that is often used for programs (java servlets, java server pages) running on the web server as well as for highly-interactive (but sometimes slow and crash-prone) java applets running on the client computer.
Although I use PHP and My SQL, most of the concepts discussed here apply equally to other languages (ASP, ASP.
NET, JSP, Cold Fusion etc.) and other databases (Postgre SQL, SQL Server, Oracle etc.).
have a listing of all employees along with separate home pages for each employee) while keeping the maintenance effort low.