The word 有效 is formed by directly combining two independent characters, each contributing its core meaning to create a new concept. The first character, 有 (yǒu), means "to have" or "to exist". The second character, 效 (xiào), means "effect", "efficacy", or "result". When placed together, the combination logically and conceptually yields the meaning "to have effect", which naturally extends to "effective" or "valid". It is a straightforward semantic compound where the sum of the parts clearly conveys the whole idea.