Glad you asked!
When you publish a landing page without setting up a custom domain, it will be published as: unbouncepages.com/yourlandingpagename.
By creating something called a CNAME (Canonical Name) record and following the three easy steps below, you can link your Unbounce landing page URL to your root domain, which will tell your domain to display your landing page at: subdomain.yourwebsite.com/yourlandingpagename.
Using your own domain instead of the default unbouncepages.com domain on your landing pages is a must before launching your campaign, and here are three reasons why:
1. Search Engine Indexing
Search engines will not index (i.e., include) pages hosted on unbouncepages.com, so connecting your domain enables your page to show up on that Google search results page.
2. AdWords Compatibility
Google AdWords requires that your display and destination URLs match, so your ad can be rejected if your pages don't appear on your own domain.
3. Telling your visitors they're in the right place
When your domain matches your brand name or campaign messaging, it creates strong brand alignment and assures visitors (who may not know what Unbounce is) that they're in the right place and they can trust the page they're on.