In the United States, a Crummey trust is a trust for the benefit of individuals into which gifts are made in a manner qualifying them for exclusion from the unified gift and estate tax.
Normally, gifts to minors are subject to parental / guardian control until the age of majority.
In order to delay the transfer of control beyond the age of 18, the funds must be placed in trust.
Normally, a gift into a trust that comes under control of the beneficiary at a future date does not constitute a present interest.
The U.S. Tax Court found this action legal in 1968, and the nickname "Crummey Power" stuck.