PTC means Paid-To-Click and as the name suggests you earn money by viewing sites.
These kind of income opportunity provides an easy way to earn money online without investments.
There is no need of advanced skills, you just need to know how to browse the net.
All PTC sites are free to join. However not all PTCs are legit and paying.
My favorite ptc site is neobux which is paying instantly since 2008 with many useful features that will increase your earnings. There are some users making thousand dollars per year on neobux and you can also replicate their success!
However to succeed at neobux you need to have a plan to make nice profits. Here you can read an efficient neobux strategy that will guide you on the right way to make money.
You can check this tutorial with the best paying PTC sites.