Hi want to Know About Pingback/trackback links

hi i have been searching for website backlinks and there are many site having same kind of links and they are ranking well. i do not know are these are good for short term. and why google do not look at this.

Please let me what is pingback .. and how to create it and is it good ?
because these kind of links so many i saw on web.

for example http://www.studentbibliotek.se/studiemedel/
http://mourningbeloveth.com/press/shapeless-2/

according to me it doesn't look good for money site but then why people getting benefit ?

wow there is no one to help?