You transfer an appreciated asset into an irrevocable trust. This removes the asset from your estate, so no estate taxes will be due on it when you die. You also receive an immediate charitable income tax deduction.
The trustee then sells the asset at full market value, paying no capital gains tax, and re-invests the proceeds in income-producing assets. For the rest of your life, the trust pays you an income. When you die, the remaining trust assets go to the charity(ies) you have chosen. That’s why it’s called a charitable remainder trust.