Pings, by their nature, are things like short sounds to detect an object, like sonar in a submarine, or short bits of data to detect if a server is online, responding, and how far distant or how quick to answer back.
Pingbacks are simply designed to automatically alert a server that you’ve linked to a WordPress post, and from what URL.
Trackbacks, on the other hand, convey a bit more information, are manually sent - not automatically, and include URL, Title and an Excerpt of the content.
Both require approval. Both are handled very much like comments. Both can frequently be used by spammers to get links back to their sites for added traffic and search rankings.
As above, 1)WordPress pingbacks are a form of automated notification system for WordPress, so that whenever you mention another site or blog post (by linking), the pingback is verified to make sure it’s not some faked entry or spam, and they get alerted to the mention (so they can approve the pingback). Both sites need to have pingbacks enabled in order for this to work. XML-RPC is the mechanism that handles the server to server exchanges.
Trackbacks, on the other hand, are not automated, are not automatically validated, convey more information than a pingback, and use HTTP Post in order to communicate with the target server.
To send trackbacks, you will need to find the trackback URL somewhere on the post page you are linking to. If you can’t find one, try to determine if the site supports pingbacks. If it does, you should not send trackbacks as well. Copy/paste the trackback URL into the Send Trackbacksfield on your Add New Post screen. If you don’t see this field, go to the screen options and select the Send Trackbacks option. Note that selecting this does not send trackbacks, it only displays the field called Send Trackbacks. When you publish your post, trackbacks will be sent to the URLs you pasted into the field. This field will also show the status of trackbacks and pingbacks on your Edit Post screen.