In case you have several domains with different extensions and you need all of them to open the very same Internet site, you could have the Internet site under one of them and redirect the others. There are different methods to redirect one domain to another, including the so-called domain parking. When your hosting plan permits it, though, it will be better if you host each of the domains and set up a URL redirect, not a domain redirect. The real difference between the two is that while a domain address is hosted, you could still have content for it, create subdomains, email addresses, etc., while with a parked domain you can't do any of these things. For example, if you're building localized Internet sites under several country-code domains, you'll be able to work on them, but at the same time, visitors will be redirected to the primary website.