A trustee is a party that has the legal authority and responsibility to manage a trust. Trusts often include various types of property that are designed to benefit beneficiaries. Trustees are tasked with making sure that the terms of the trust are followed and that the beneficiary or beneficiaries will benefit as per the trust terms.
Trustees are used as third parties between the grantor of the trust and the beneficiary. When a grantor sets up a trust, he or she is trusting the third party to execute the trust properly. For example, a grandfather may set up a trust for his grandchild with the terms that the grandchild shall receive $5,000 every year after the grandchild turns 18. The trustee would be responsible for seeing that the account pays the $5,000 a year to the grandchild upon the grand child's 18th birthday.