WordPress normally not allowing you to add Php codes  to pages and posts, It's where shortcodes comes in. when a shortcode is encountered within post text then any custom php codes can be executed.

It's a common task that you need to check if your single checkbox 

is checked or not before doing something with that.

Adding scripts and styles in wordpress is different from 

what we do in a normal php sites of course.

Making a contact form is very popular in wordpress. 

Following code shows how i made a contact form.

If You want to become a good web developer, 

you have to learn to write secure code perfectly. 

A php array is called a special variable, which is able to hold 

more than one value at a time.

JSON is JavaScript Object Notation 

Here is the simple coding on how to code do calendar programming using php..