In case you have a few domains with different extensions and you need all of them to open exactly the same website, you may have the website under one of them and redirect the rest. There are a number of methods to redirect one domain to another, such as the so-called domain parking. When your hosting plan permits it, though, it will be better if you host each of the domains and create a URL redirect, not a domain redirect. The main difference between the two is that while a domain name is hosted, you can still have content for it, create subdomains, e mail addresses, and many others., while with a parked domain you cannot do any of those things. As an example, if you are building localized sites under different country-code domain names, you'll be able to work on them, but in the meantime, people shall be forwarded to the primary website.