Dr. Andrew C. Skinner, currently executive director of The Neal A. Maxwell Institute for Religious Scholarship at BYU, gives a good and succinct definition and description of what an LDS temple is over at the MormonChurch.com blog. Such an answer would be good for those who question us what the temple is all about.
Here is an excerpt:
Latter-day Saint or Mormon temples are holy edifices or buildings wherein the most sacred ordinances, rites, and ceremonies are performed that pertain to full and complete salvation in the Kingdom of God, usually referred to as exaltation. Because Latter-day Saints believe that life continues after this mortal existence, and that all men and women deserve and need to participate in these saving ordinances instituted by God, members of the Church who have participated in these ordinances for their own salvation are encouraged to return to the temple often to act as proxies for ancestors who have passed on. . . .
Read the rest here.