What is a parked domain

A parked domain name is one that's taken, but it is not connected to any other service - web or email hosting. To put it differently, such a domain won't open any actual content when you type it inside a browser, but no one else can take it as you've already registered it and you are its owner. The best thing about getting a domain name and parking it afterwards is the fact that you’re able to keep it and not worry that someone else could possibly register it meanwhile if, for instance, the site for it is not ready yet. You are able to set a temporary Under Construction webpage for a parked domain while you are working on your site, or direct it to another web address - temporarily or permanently. The second option can be employed when you have already registered domain.com, for example, and you obtain domain.net and domain.org, in order to protect a brand name or a trademark. In this case, the .net and .org domain addresses can be parked and forwarded to the .com as you do not need different websites for them. 

I use domain parking program from the-online.com which pays me ppc revenue quite higher than parklogic or bodis or sedo. The RPM/CPM is about $9 for top tier countries like Canada, US, UK. They pay for ad impressions and not click. My daily revenue is about $25 from single domain (and I've 7 domains parked with them). All you have to do is to register or transfer domain which has traffic, (or you can buy traffic from google ads, or facebook ads and divert to your parked domain.) and apply to the-online.com by email, and they'll send you form to fill. In two days they approve it. Just don't use adult themed domains. Use clean domains only.