PTC websites, act as middlemen between advertisers and consumers; the advertiser pays for displaying ads on the PTC website, and a part of this payment goes to the viewer when he views the advertisement...
You can earn money simply by click Ads on PTC sites .. but becareful coz many PTC is a "Scam"..
Dont worry I will give you a hint...
1. Before you join a PTC, make sure it Scam or not by doing search in google "XXX SCAM" change XXX with the name of PTC you want to join. If the result searching too many website or blog expose about it, just leave it. Dont ever Join that Site
2. Come in to PTC website, check first the forum active or not, if there is no posting about activity member, administrator and anything, just leave it. You can see payment proof in here too...
3. Check the payment proof update,See the last payment proof. Payment proof usually used paypal, alertpay, liberty or anything.
4. See the appearance website design, if the design standard may be you can thinking more.
5. Check earning how many you will get for every clicked ads, if too big and not real for your think leave it. this time average PTC give us earning every click ads between $0.01 or less .
6. Read Tos(Term of Service) carefully. :)
List of below is PTC I join and I Recommended... Trust Me ...!!
1. NeoBux
Neobux is the Number 1 PTC in the world Click the banner below to join
2.OnBux
Many People called this site as the second NeoBux Click Banner to Join
3. IncraseBux
This one is often called as second NeoBux too
4. Cashium
The New Element of PTC ...

5, PalmBux
New trusted PTC
6. SedoBux
This One is Great too...