I
think that
Lewis Carroll invented these. Example
(HATE->LOVE):
HATE
HAVE
HIVE
LIVE
LOVE
Here's another (BURN->MELT):
BURN
BORN
BORE
MORE
MOLE
MOLT
BOLT
BELT
MELT
By changing one letter at a time you form new words and eventually arrive at a specific word. Preferably in the fewest possible steps.