Just how important is the Deed to a house?

When my dad bought a house and he was signing his name with my mom on different sections of a thick stack of papers called a deed. I was 15 years old and had no clue what a deed really was about. I thought it was some thick stack of papers that was worthless as a receipt from grocery stores. Do deeds have legal power in them? What happens if you tear up your own deed when you buy your own house (does it go to auction or what)?