In case you have several domains with different extensions and you need all of them to open exactly the same Internet site, you can have the website under one of them and redirect the rest. There are various methods to redirect one domain name to another, among them the so-called domain parking. If your hosting package permits it, though, it'll be better if you host all the domains and set up a URL redirect, not a domain redirect. The primary difference between the two is that while a domain is hosted, you can still have content for it, set up subdomains, email addresses, and many others., while with a parked domain it's not possible to do any of those things. As an example, if you're building localized websites under different country-code domains, you shall be able to work on them, but meanwhile, visitors shall be forwarded to the primary site.