Trunks is the son of Bulma and Vegeta. He's half Saiyan and fights well
like his father.  He usually carries a sword on his back, which he got
from Taggeria.

Mirai Trunks first appears in Dragon Ball Z at about the end of the Freezer
epsiodes, where he of course kills him by splitting him in half
(gruesome!). He came from the future to save Gokou from dying in order
to save the future from the Androids, who in his time were destroying
the earth and no one could stop them.

In the future, Androids 17 and 18 escaped and are basically wiping out
the entire planet, one city at a time.  Of course, everyone tries to
stop them, but no one succeeds.  Gokou could, but sadly he contracts a
heart disease and dies =( So Gohan tries to train Trunks and get him
to Super Saiyan level.   
          

Yeah, I know this is pretty vauge.  I'll have more soon