What is the difference between PHP, ASP.net and Java script?

PHP and ASP are server side languages. The processing is done at the host computer.

Javascript is a client side language. It's not a full language, so relies on something else like HTML to develop the page.

JAVA is a full language that works for developing applications or websites.

Which to choose depends on what you want it to do and what you want to spend.

If you are storing a lot of customer data, then you'd want to be server side.

A lot of flashy presentation but not much change in content would be better suited for client side.

ASP,ASP.Net,PHP, and coldfusion are all server side development tools that allow you to create a much more dynamic site based on information you may have on the server such as the use of a database.

Java is a programming language that has multiple purposes, it is used by JSP which is another server side development tool.

JavaScript is a programming language that can be used by ASP, but since ASP is loosing popularity to ASP.Net, Javascript is mostly used on the client's computer to provide a more interactive experience, especially when making use of Ajax, which ties together the use of Javascript on the clients computer and one of the server development environments.

PHP, and JSP can be deployed using open source free software, if you run linux, since linux, and the JSP, PHP software can be obtained free of charge.

For a simple dynamic web site, I would suggest going with PHP since it's free, and it can run on linux, it's relatively simple to setup and use when compared with the other technologies available, and still provides a very good base for developing websites. You'll need to learn a bit of javascript as well since this is the client technology heavily used.

both php and javascript are extensions to html. Javascript is not java - java is another language completely. javascript is a lot more basic, and can be seen by the viewer. It is usefull for making things happen instantly such as pictures following your cursor, moving parts, and timers. javascript can be put in a normal html file php is more advanced and can be used to connect to a database and return (echo) information back. The reason veiwers cant see your php code is because php builds the html file (server-side) and sends only the html/javascript back your audience (hence Personalized home page)

You don't /need/ to know any of them to build a website.

ASP and ASP.NET are server side environments in which you can run programs, typically written in C# (ASP.NET) or VBScript (ASP).

PHP, Java, and JavaScript are all programming languages. They can all run on the server.

Java and JavaScript can also run in the browser (although support for Java Applets is generally weak these days).

ColdFusion is a tag library for Java. It adds some shortcuts when writing server side Java.

Right now, of all these languages PHP is probably the most useful to 'know' and has a lot of support on Forums and community pages if you need help constructing a particular function.

Client side languages are handy for making a site look good and perform certain tasks in relation to a users input, however security 'upgrades' in certain browsers (yes, I'm looking at YOU Internet Explorer...) can mean that certain elements you design are seen as a security threat and disabled. Quite frustrating.

It's really going to come down to what you need / want the website to do as to which language works best for you. but as a quick guide Look at the following pages (saves me having to type up complicated explanations) :

PHP - http://en.wikipedia.org/wiki/.php

ASP - http://en.wikipedia.org/wiki/.asp

Java - http://en.wikipedia.org/wiki/.java

Javascript - http://en.wikipedia.org/wiki/Javascript

Coldfusion - http://en.wikipedia.org/wiki/Coldfusion

These pages will give you a good idea of what does what and when to use it.

Enjoy your studies!

If you would like to build a dynamic website, I recommend PHP all the way. Don't use ASP.Net, its slower and there's more of a community for PHP. PHP can also run completely free. That is, ASP can't run on Linux (free) PHP can.