Rice Theorem - What is non-trivial property?

Question

Every nontrivial property of the recursively enumerable languages is undecidable.

What exactly is nontrivial property?

Answer 1

A property that holds for every machine or holds for none is trivial. Rice's theorem does not apply to such a property.

To see why, note that such a property can be decided by a very simple Turing machine, which accepts/rejects every Turing machine representation.