A parked domain is a registered domain name which has not been thoroughly developed but confided to a parking domain service to generate revenues through PPC ads. There are millions of parked domains on the Internet but the golden age has passed. However, some domainers still make a living on parked domains. For more details and illustrations see domain parking.
The parked domain term can also be used sometimes to refer to an accessible domain waiting to be developed without any intention to generate revenue. In this case, there is no ads on the website.
Parked domains are often considered as an issue for PPC advertisers as they are a traffic source with low conversion rates - see search syndication for more details.
Parked domains are easy to recognize as their sole content is made of PPC ads or category links leading to ads and of a search box.
Some examples of parked domains: