What is visualforce?
Visualforce is a markup language that allows defining user interface components in Salesforce. This is a very interesting tool which runs o force.com platform. By using page layouts, we can easily configure the User interface. But by using visualforce pages, you can develop your own customized user interface.
Here in Visualforce Tutorial, I am providing information about, how to work with visualforce pages. Hope this will help you to understand basic of visualforce pages.
Visualforce Tutorial
Introduction to visualforce pages
Custom controllers & Controller Extension
How to display visualforce page as a pdf?
apex:selectList with standard list Controller – SalesforceTutorial
<apex:actionFunction> tag in visualforce page
<apex:actionPollar> tag in visualforce page
<apex:actionStatus> tag in visualforce page
Overriding Standard button with visualforce page
Visualforce page to add multiple records
Disabling the command buttons and Grey out the total vf page on any action
how to hide approve/Reject links in the home page?
How to display alert on Salesforce standard/custom object page layouts?
How to use reRender & rendered attributes?
Salesforce Visualforce Page Tags
Above are the few examples to understand visual force basics. To learn more about visualforce page see salesforce vf guide