Part of the problem here may be that "tautology" has a far more specific meaning in mathematical logic than in ordinary usage. The more specific meaning is "a statement S that always true, solely on the basis of how S is constructed from smaller statements by means of propositional connectives and the meanings (truth tables) of the connectives". So $A\lor\neg A$ is a tautology because it is true solely because of the meanings of $\lor$ and $\neg$. But $1=1$ is not a tautology because its truth depends on the meaning of $=$, which is not a propositional connective. Similarly, if $P$ is a unary predicate, then $P(a)\to(\exists x)\,P(x)$, though logically valid, is not a tautology because its validity depends on the meanings of both $\to$ and $\exists$, the latter of which is not a propositional connective.
In ordinary, non-technical usage, "tautology" means (according to my dictionary) saying the same thing in different words; I've heard it used more generally to mean anything that is obviously true. So all of the examples in my first paragraph would be tautologies in this sense.