Tax Deed
  
See: Tax Lien Foreclosure.
You didn't pay your property taxes. The government eventually seized you house (hope your sister has some room in her garage).
The document giving the government ownership of your home is called the tax deed. However, the government doesn't really want your place. It just wants the tax money. It wants cash in order to pave streets or build firehouses or to buy a new sash for next year's Miss Peach Blossom.
So...it's not like the mayor and city council president are going to move into the place. The government plans to sell your house at the earliest possible time. The tax deed gives them title, which will quickly get transferred to whoever buys it at auction.