In case you have a few domain names with different extensions and you need all of them to open the exact same website, you can have the website under one of them and forward all the rest. There are a number of ways to redirect one domain name to another, like the so-called domain parking. If your web hosting package deal allows it, though, it'll 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 may still have content for it, set up subdomains, e-mail addresses, and so forth., while with a parked domain it's not possible to do any of those things. As an illustration, if you're building localized sites under several country-code Internet domain names, you shall be able to work on them, but meanwhile, visitors will be forwarded to the main Internet site.