"Trackback" is the name of a new system for making connections to other persons' daybooks. If you come across an interesting writing when you are reading someone's weblog, you may put your opinion about her or his writing, with a bookmark, onto YOUR weblog, send a special sign named "ping" to the special place which takes care of the connection, and then you will see a short statement under the interesting part on HIS or HER weblog.
http://ohyama.way-nifty.com/in_basic_english/2005/03/ryotasans_blog_.html
http://ohyama.way-nifty.com/days/2005/03/ryota.html