A bankruptcy trustee, usually an attorney or accountant, is appointed by the United States Department of Justice or by the creditors involved in a bankruptcy case. In a chapter 7 bankruptcy, the trustee reviews your assets and determines which are non-exempt. Most likely in a chapter 7, there are no non-exempt assets. But, if there are, then the trustee is responsible to make sure the assets are sold/liquidated and the proceeds go to the creditors. Sometimes, in lieu of a sale or liquidation, the trustee can set up a payment plan from the debtor to address this non-exempt property. For example, instead of forcing the sale of a non-exempt timeshare, a trustee can set up a payment plan from the debtor to satisfy the excess value.
The role of a trustee in a chapter 13 bankruptcy is more involved. The trustee must approve your repayment plan and receives your agreed upon monthly payments, which are then distributed to the creditors.
It is important for the debtor to remember that the trustee works for the creditors. Therefore, it is in the best interest of the debtor to hire a bankruptcy attorney who is familiar with the process of dealing with the trustee and who will attend the meeting (called 341 meeting and/or a "Meeting of the Creditors") with the trustee.