Trackbacks are the process of tracking when somebody has linked to your site. It is a way that you receive notification on your blog that somebody has linked to you.
A trackback does not require sites to link to each other – it is simply a signal sent from one site to another – and usually a receptor publishes a link back to the originator.
Both sites need to be on a platform that allows trackbacks for this to happen.
Basically, trackbacks help communication between blogs – it allows a blogger to write a post referring to another blog and pinging that blog to let them know “hey I’ve written a post referring to your blog post.” It allows you to see that someone has written about your post online.
Trackbacks are usually listed under the posts where the comments are placed.
Basically a trackback is an offsite comment – instead of reading the persons comment, readers can go off your site and read a whole article referring to your post – this is great for conversations that run through numerous blogs.
It is also a courteous way of telling someone that you wrote about them or what they wrote about – allowing them the opportunity to participate in the conversation.