Parked Domain
A parked domain, sometimes called an alias, is a second domain attached to your hosting account with no website of its own. Anyone who types it sees the primary domain's content: same site, different address.
At the DNS and web server layer
Two layers are involved. In DNS, the parked domain's A record points at the same IP as the main domain. At the web server, the parked name is added as a ServerAlias on the same virtual host, so its requests are served from the main domain's document root. There is no separate folder or app.
In cPanel you add it under Domains as a parked domain. Some panels can aim it at a specific folder, but that is advanced use. Because both names are served by the same application, the server answers each with an HTTP 200, so cookies, sessions, and CMS settings are shared. You only get a separate install once the name is converted into an addon.
Parked, addon, and redirect
The difference matters for SEO. A parked domain serves duplicate content at two addresses, while a redirect names one official address. If the goal is to steer traffic, use a 301 redirect instead of parking.
When parking helps
Brand protection: buy the .net, alternate spellings, or local extensions and park them so nobody else takes them. Temporary campaigns: an event domain whose content is not ready, pointing at the homepage for now. A rebranding runway: the new name is bought before the new site is ready. Note that a parked domain still renews every year, and parking does not make it free.
Consequences to expect
Two addresses with identical content confuse search engines over which version is official. Add a canonical URL tag to mark the preferred one, but the cleaner fix is a 301 to the main domain. Do not read "unlimited parked domains" literally; such plans still carry fair-use resource limits. In many panels you also need to register both the www and bare form so each resolves correctly.
FAQ
Does a parked domain use resources?
Very little. Requests still hit the server, but there is no extra app to run like an addon has. What you pay yearly is the domain renewal.
Can I turn a parked domain into an addon?
Yes. Usually you remove the parked entry and re-add the name as an addon. Its files start from scratch, and email plus SSL need configuring again.
How is this different from a registrar parking page?
A registrar parking page shows ads or a "domain for sale" note. A parked domain on your account sends visitors to your own site.
Disclaimer: Hosting Wiki articles are prepared for educational and reference purposes. Hosting technology keeps evolving, so some technical details may change over time.