Web Development is the back of the website where coordinating between pages and programs is useful for the visitor's work. And the web developer is the person who makes the website useful for the visitors. A good developer knows how a website works for you.
But one of the interesting things is that you will not find any web designers who have no idea about JavaScript, PHP, and HTML. Now you will not find any web developer who does not know about web design.
To learn web development, learn all that HTML, CSS and then the following.
Client-side programming languages such as JavaScript:
It is called browser scripting and means that the code written with this language will work only in a browser (such as Internet Explorer, Mozilla Firefox, Opera, Google Chrome etc.). JavaScript frameworks can be used quickly. A framework such as Jquery Tutorials
Server side programming language such as PHP:
This is called Server Side Scripting because the code written with this language is only executed on the server.
Databases:
How to connect databases with PHP, creating databases with SQL means that you should know databases design because now there are databases of any dynamic site or you can say databases.
Any PHP framework such as Codeignetter: (There will also be a learner like CakePHP, Zend Framework, Simfoni, YiI, Kohana etc.): You can create web applications in addition to any framework, but it will take longer and write more code.
XML:
XML is required to create web applications.