What are all the things that one must know and understand to become a web developer from naught?

There so much to do .. This answer is in context that you want to become a Web Developer which is not be confused with web designer. Front-End / UI / UX : Necessary : HTML, CSS (maybe even CSS3),  Javascript, A javascript framework (JQuery, Mootools anyone really). Advanced : Compass, SASS, Front End Frameworks like Backbone.js, Knockout.js, Node.js. Bonus: Photoshop, illustrator Back-End : This would rather be in terms of paths. PHP -> Object oriented PHP -> PHP Frameworks (Laravel, Codeignitor) Java -> J2EE -> Spring framework Ruby -> Ruby on Rails There are just too many to list here ... And this is just normal websites .... I haven't listed CMS related development (Drupal plugin Development or Wordpress themes) ... there is so much to do in just one area Then there are web apps, chrome extensions, add-ons. Let me know if you need a detailed list of things you are interested in.... Hope it helps UPDATE : i will come back to this answer and update it from time to time and make an exhaustive list of things along with possible time frame to learn them.

- Front End: HTML5, CSS3.0, JavaScript, Jquery or any other javascript framework. i prefer JQuery... and also photoshop or fireworks - BackEnd: PHP or Ruby or Python or Java. i prefer PHP and i use it a lot. -Database: MySQL, Oracle DB, MSSQL, PostgreSQL etc. i prefer MySQL. -Frameworks: codeigniter, JoomlaCMS, Drupal, opencart, prestashop etc. they make your work easier if you know how to use them ofcourse... for time frame required to learn this: maybe a month or two should make you better at knowing most of this technology. if you dont focus much on writing boilerplate code, you can breeze through most of them within weeks

I hope you're well! From my understanding web designer typically means front-end developer. I'm assuming you mean overall front and back-end, server maintenance, etc. I would identify what kind of technologies you levitate towards. Having a java background, I think you can adapt to many development languages. Since you're starting out, I would recommend signing up for something like http://teamtreehouse.com They have good overall classes from everything to front to back-end, how to run a business, etc. They even have tracks and recommend courses depending on what your focus is in the immediately. You can add to it over time. I hope that helps!