There are many ways to earn money online for free. I am trying to explain some methods that can work for you. Before you start making money online for free with out any investment you require following things.
1. Bank Account
2. PayPal Account (PayPal is widely used online payment processor. You can say it as Online Bank)
3. Computer & Internet
4. Time
5. Professional Skills (Optional)
6. Website or Blog (Optional)

Some popular ways to start making money online

To start online income here I am mentioning some methods which easy to start.

1. Earning as a Freelancer (Skills Required)

2. Affiliate Earning

3. Earn as PPC (Pay Per Click) Advertising Publisher  (Required Website or Blog ( You can make a blog for Free)

4. PTC (Paid To Click) Earning