A Counter entity provides a counter, which will be incremented depending on the value of fields in a submitted form. You can use counter entities among other things to add voting features in your page, as well as a wide variety of counters only limited by your own imagination.
The counter entities has a dialog where you can specify which argument should be used as basis for the counting, as well as what value it should contain in order to count. You can also change the value of the counter itself from the dialog. The counter is incremented whenever an argument posted to a location contain a specific value.
Here is an example of a form that affect a counter:
Do you agree?