An addon domain is a domain name that points to a subdirectory within your account. For example, you may want innovation.org.in to point to business.org.in/innovation/ .
Addon domains must be registered domain names that you own and configured to point to your web site’s servers.
When visitors reach your addon domain, they will not realise that it is an addon domain. The addon domain will act as an independent domain, with no link to the primary domain.
E.g. you have a primary domain xyz.com, which has a folder “addyes”. if you assign the addon domain mno.com to the folder “addyes” the following URLs will all lead to the same locaton.
All three of these paths would access the same directory and show the same website. For visitors going to mno.com, there is no evidence that they are being routed via xyz.com/addyes.