The way that I understand when you leave a link on a site that it counts as a back link only if the S/E's connect the dots. I have done this on several occasions as well as paid to get several links but I am not sure that the search engines are recognizing them as such to my site.
I have have heard different explanations but none that really made sense until today.
When you ping a link it is like putting the red flag up for the mail man to know that you have info that needs to be delivered.
Now the real question I am trying to understand is how do you ping and make sure the red flag is up?