A trust is a private legal construct (in this case established under the laws of Virginia, USA) allowing assets (in this case, intellectual property rights and other property) to be held and administered for specific purposes (in this case, for the benefit of the IETF and hence the Internet standards process). A Trust is normally managed by a set of Trustees who are obliged to follow the terms of the Trust Agreement.
The IETF Trust was formed in 2005. See BCP 78 and BCP 101 for more details on how and why it was created.
Here’s how to contact the Trustees:
trustees@ietf.org
IETF Trust
c/o AMS
5177 Brandin Ct
Fremont, CA 94538
Phone: +1-510-492-4080