The Data Owner is primarily responsible for defining the classification of the data, setting sharing permissions, and overseeing the data throughout its lifecycle. They make decisions about who can access the data and how it will be handled or protected based on organizational policies. Custodians or Stewards would handle data as per the instructions of the Data Owner, but the ownership and decision-making responsibility lies with the Data Owner. Processors might process the data but do not define its classification, permissions, or lifecycle management. Data Controllers typically determine the purposes for which and the means by which personal data is processed, but this does not necessarily include defining its classification level or handling its lifecycle.