A system for identifying keywords which may include a non-acquiescence information collector operative to collect information indicating, for each individual website from among a multiplicity of websites, at least one keyword which brought at least one user into contact with said individual website but did not result in a defined criterion for acquiescence of a user to at least one suggestion presented by said website; and a negative keyword definer operative to define at least one specific keyword which brought at least one user into contact with a specific website but did not result in a transaction between said user and said website, as a negative keyword for said specific website. Positive keyword extraction based on aggregation of visitor acquiescence information may be provided. Paradigm structuring may include template generation of invitations and/or attribute based generation of invitation cueing sets.