Drupal gives you the option to have several different sites under one Drupal installation using different databases (or database prefixes) for each site.

Let's say that you have two domains - domain1.com and domain2.com; domain1.com is your main domain and domain2.com is a secondary domain. To create two different Drupal sites for domain1.com and domain2.com, follow the steps below:

• Step 1. Install Drupal at domain1.com.
• Step 2. Create a new MySQL database and user. They will be used for the new site domain2.com.
• Step 3. Create a directory /sites/domain2.com/ inside your main Drupal folder (public_html most probably).
• Step 4. Copy /sites/default/default.settings.php to /sites/domain2.com/
• Step 5. Park domain2.com to domain1.com
• Step 6. Go to http://domain2.com/install.php and complete a new installation for domain2.com with the Mysql details from Step 2.

That's it! If you want, you can create more Drupal multiple sites following the steps above.