Entrecard is the first and only free exchange network for 125×125 ads. Through this revolutionary platform, you can advertise your own 125×125 Entrecard on any blog in the network, for free, for a number of days.

You pay for this advertising with Entrecard Credits, that you earn for free by networking (a.k.a. visiting blogs and dropping your card for other bloggers). Credits are the currency of the Entrecard network. You spend them to advertise your Entrecard on other people’s widgets.

How are credits earned?

• You earn 1 credit every time you drop your card for someone else.
• You earn 1 credit every time someone else drops their card for you.
• You earn credits every time someone advertises on your widget.

Type: Free Exchange Program
Source: http://entrecard.com/