There are a lot of ways to forward traffic from one domain/website to another. The so-called URL redirection is often favored. In contrast to parking a domain, a URL forwarding can be done only if the domain in question is hosted. What this means essentially is that you can still open any content if you have a direct link to it and you may set up e-mail addresses or subdomains and use them. Such a function has many practical uses - if you decide to switch your domain name, you can redirect the visitors, but the emails with the old one shall still be active in case you are making contact with clients or partners. When you have 2 identical sites and you intend to rebuild one of them, you can redirect the site visitors to the other site so that you can prevent losing potential customers, while you will still be able to access the administration area for the first site and improve it.