A trust is a written agreement designating someone to be responsible for managing your property.
It's called a living trust because it's established while you're alive. It's "revocable" because, as long as you're mentally competent, you can change or dissolve the trust at any time at your own discretion for any reason.
Typically, a living trust becomes irrevocable (cannot be changed) when you die.
A trust involves three parties:
1) you as the creator
2) the trustee or trustees who agree to manage the assets as directed by the terms of the trust
3) the beneficiaries.