A testamentary trust is a legal arrangement created through a person's will, which comes into effect after their death. This type of trust allows the deceased to specify how their assets will be managed and distributed to beneficiaries, often providing for minors or individuals who may not be financially responsible. The trustee, appointed in the will, is responsible for managing the trust according to the deceased's wishes. This arrangement can help protect assets, minimize taxes, and ensure that beneficiaries receive their inheritance over time, rather than in a lump sum, promoting financial stability.