What is Visualforce?

Visualforce is a framework that allows developers to build sophisticated, custom user interfaces that can be hosted natively on the Lightning platform. The Visualforce framework includes a tag-based markup language, similar to HTML, and a set of server-side “standard controllers” that make basic database operations, such as queries and saves, very simple to perform.

In the Visualforce markup language, each Visualforce tag corresponds to a coarse or fine-grained user interface component, such as a section of a page, a related list, or a field. The behavior of Visualforce components can either be controlled by the same logic that is used in standard Salesforce pages, or developers can associate their own logic with a controller class written in Apex.

Sample of Visualforce Components and their Corresponding Tags

An Apex page with callouts to the apex:page, apex:commandLink, apex:image, apex:relatedList, apex:pageBlock, apex:dataTable, and apex:detail tags.

What is a Visualforce Page?

Developers can use Visualforce to create a Visualforce page definition. A page definition consists of two primary elements:

1. Visualforce markup

2. A Visualforce controller

Visualforce Markup

Visualforce markup consists of Visualforce tags, HTML, JavaScript, or any other Web-enabled code embedded within a single <apex:page> tag. The markup defines the user interface components that should be included on the page, and the way they should appear.

Visualforce Controller

A Visualforce controller is a set of instructions that specify what happens when a user interacts with the components specified in the associated Visualforce markup, such as when a user clicks a button or link. Controllers also provide access to the data that should be displayed in a page, and can modify component behavior.