This tutorial is for Joomla! CMS Version(s) 
This tutorial is part of the Developing a Model-View-Controller (MVC) Component for Joomla!2.5 tutorial.
Let's create a Hello World! component.
With your favorite file manager and editor, create a file yoursite/components/com_helloworld/helloworld.php containing
Hello world
You can test this basic component by putting index.php?option=com_helloworld in your browser address (don't forget to prefix this address with your Joomla!2.5 installation path) after installing this component.
With your favorite file manager and editor, create a file yoursite/administrator/components/com_helloworld/helloworld.php containing
Hello world administration
You can test this basic component by putting administrator/index.php?option=com_helloworld in your browser address after installing the component.
If you have used Joomla before reading this tutorial, you have noticed that extensions are installed using a compressed file containing all the things which are needed for installing and uninstalling them.
With your favorite file manager, create a directory (outside your Joomla installation directory) containing
admin/sql/updates/mysql/0.0.1.sql is an empty file allowing to initialise schema version of the com_helloworld component.
admin/sql/updates/mysql/0.0.1.sql
Create a compressed file of this directory or directly download the archive and install it using the extension manager of Joomla. You can test this basic component by putting index.php?option=com_helloworld or administrator/index.php?option=com_helloworld in your browser address. You can also notice that the Hello World! component is visible in the administrator site of your Joomla installation under the Components menu.
helloworld.xml
<?xml version="1.0" encoding="utf-8"?> <extension type="component" version="2.5.0" method="upgrade"> <name>Hello World!</name> <!-- The following elements are optional and free of formatting constraints --> <creationDate>November 2009</creationDate> <author>John Doe</author> <authorEmail>john.doe@example.org</authorEmail> <authorUrl>http://www.example.org</authorUrl> <copyright>Copyright Info</copyright> <license>License Info</license> <!-- The version string is recorded in the components table --> <version>0.0.1</version> <!-- The description is optional and defaults to the name --> <description>Description of the Hello World component ...</description> <update> <!-- Runs on update; New in 2.5 --> <schemas> <schemapath type="mysql">sql/updates/mysql</schemapath> </schemas> </update> <!-- Site Main File Copy Section --> <!-- Note the folder attribute: This attribute describes the folder to copy FROM in the package to install therefore files copied in this section are copied from /site/ in the package --> <files folder="site"> <filename>index.html</filename> <filename>helloworld.php</filename> </files> <administration> <!-- Administration Menu Section --> <menu>Hello World!</menu> <!-- Administration Main File Copy Section --> <!-- Note the folder attribute: This attribute describes the folder to copy FROM in the package to install therefore files copied in this section are copied from /admin/ in the package --> <files folder="admin"> <!-- Admin Main File Copy Section --> <filename>index.html</filename> <filename>helloworld.php</filename> <!-- SQL files section --> <folder>sql</folder> </files> </administration> </extension>
site/helloworld.php
Hello World
admin/helloworld.php
Hello World administration
index.html common to all folders
<html><body bgcolor="#FFFFFF"></body></html>
Next: Adding a view to the site part