A trust is a legal arrangement that allows you to gift the cash lump sum payable from your life insurance policy to your chosen beneficiary/beneficiaries. Once you have done so, the policy is looked after by a third party, known as the trustees, chosen by you. By placing the insurance policy into trust, you effectively give up ownership of it to the trustees for them to hold for the beneficiary/beneficiaries.
If the policy has already been set up, you can still, in most circumstances, draw up a lifetime trust to capture the policy proceeds on your death which essentially remains dormant unless and until a lump sum is paid to the trustees of the trust on your death.