PTC stands for Paid to click.
Paid-To-Click is an online business model that draws huge amounts of online traffic from people aiming to earn from home. Paid-To-Click, or simply 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 consumer when he views the advertisement.

The viability of the PTC business model has been questioned, as fraudulent clicks have ramped up the expenses for advertisers. With lawsuits filed against the internet search companies, the burden has been placed on Google, Yahoo and others to determine the valid clicks from the fraudulent ones, although PTC site may just be used as advertising, to direct traffic to one's site. Moreover, many users registered in PTC websites are bots.

Even though advertisement is the most widely known method for PTC to stay alive, most of the profit comes from the direct sales of fake referals which are created virtually by the PTC owner at his will. To cover up all this scheme, PTC owners inject some normal ads from fictional advertisers thereby keeping the system running smoothly.

Some PTCs are also used to mimic mass human traffic which can help a botnet stay undercover and perform click fraud activity in 2nd and 3rd tier ad networks. Many PTC owners also pollute the ads with malware and botnet rootkits.

Scams although exposed on various PTC forums are still heavily used by new-comers who are drawn in to the websites by search engines. Scam PTC sites are known to attract new users with cheap offers for upgrade and referrals and disappear without trace after a short time.