I am really confused about web application development. I read w3 and apple choose and recommend javascript for developing web apps but i heard that for developing web apps i need to create back-ends with Java. Can I learn html5/css3/javascript and develop a complete webapps by only using those technologies?
Thanks
You can have a fully functional website without any server-side scripting. That said, if you're trying to create an application that works with data, you're going to need, at the very least, a database and server-side scripting to interface with it.
Not to be rude, but based on your question, I doubt that you're at that point yet.
It really depends on what you are creating. But for the most part no. You are going to need some backend storage, this is usually done through PHP/MySQL. However, the actual application is created with html5/css3/javascript, and lots can be done just with that. Why you hear about backends is if there is a lot of data to process or some type of expensive computation it is sometimes better to do it serverside with C++ or Java or some other programing language. I hope this answers your question.
Think of it as a circle. The backend language, be it PHP, ASP (.net) Java, etc it all exists to help the backend build the frontend. HTML, javascript, CSS is basically the frontend. Sure, you can do a website solely in HTML and CSS, but without the backend code, we'd be building pages that are essentially static. The user interacts with the application, which goes back to the server and is processed and so on and so forth....hence the circle.
HTML can't talk directly to a database, which is essential to most apps out there. Hence the reason it's near impossible to get away from back-end development.
I've worked in a Java shop before...the reason many big operations use it is because it's considered in many circles to be "enterprise grade" The US Government, banks, perhaps even Apple rely on it to power their corporate apps and websites in many cases. Java is the basis for other languages, and its structure and nuances are copied in many other systems. One can make a lot of money programming it.....but having been there, I know it can also be bloated, fickle, and inefficient. Java is most definitely not Javascript.
If you are trying to cut down on the number of languages you need to learn, you might consider the Myna Javascript Application Server. That way you can write both the front- and back- end in JavaScript. Myna also comes with an embedded database so there is no need for other software for simple sites. See this question for more detail about server-side JavaScript.