A method and a system are provided for targeting online ads by grouping and mapping user properties. In one example, the system receives user data associated with one or more users. The system identifies user properties for a user. The system eliminates unacceptable user properties associated with the user. The system identifies permutations of the user properties associated with the user. The system eliminates unacceptable permutations of the user properties associated with the user. Valid permutations remain. The system attaches a weight of importance to each valid permutation. A weight quantifies a level of importance of a valid permutation for the user with respect to buckets. A bucket is an ad category. The system grades each valid permutation relative to a bucket. The system calculates a final grade for each bucket. The system then assigns the user to zero or more buckets based on the final grade for each bucket.