People often think they need a Trust when they don’t. It does depend on how large there estate is; are there minor children; are there special needs children or adults; are there situations where you don’t want someone to receive a large amount of money all at once.
And they’re ‘revocable’ in that whoever establishes the Trust can change it any time without permission of a beneficiary. Last Wills and Testaments, if filed with a court after a death, are available to the public at large. Trusts are not.