and: used to connect words of the same part of speech, clauses, or sentences that are to be taken jointly
or: used to link alternatives
Sometime we write "and/or" but wouldn't that be logically same thing as saying "or"? It seems that if we meant XOR, we'd have made it explicit instead of explicitly making the assertion that it can be either one of, any combination of, or all of the choices as we do with "and/or". Am I misguided in wondering if it's perhaps incorrect usage?