If you have several domains with different extensions and you want all of them to open precisely the same site, you can have the website under one of them and redirect the others. There are various methods to redirect one domain to another, among them the so-called domain parking. When your web hosting package deal allows it, though, it'll be better if you host all of the domains and create a URL redirect, not a domain redirect. The 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 you can't do any of these things. As an illustration, if you're building localized websites under different country-code domain names, you shall be able to work on them, but in the meantime, visitors shall be redirected to the primary website.