In case you have a number of domains with different extensions and you want all of them to open the same site, you could have the site under one of them and forward the rest. There are several ways to forward one Internet domain name to another, among them the so-called domain parking. If your hosting plan allows it, though, it shall be better if you host each of the domains and create 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, set up subdomains, e-mail addresses, and many others., while with a parked domain you can't do any of those things. For example, if you are building localized websites under various country-code domain names, you shall be able to work on them, but at the same time, visitors will be forwarded to the primary Internet site.