A social skill is any
Social skills are the tools that enable people to communicate, learn, ask for help, get needs met in appropriate ways, get along with others, make friends, develop healthy relationships, protect themselves, and in general, be able to interact with the society harmoniously.  Social skills build essential character traits like trustworthiness, respectfulness, responsibility, fairness, caring, and citizenship. These traits help build an internal moral compass, allowing individuals to make good choices in thinking and behavior, resulting in social competence.
Social skills are goal oriented with both main goals and sub-goals.  For example, a workplace interaction initiated by a new employee with a senior employee will first contain a main goal. This will gather information, and then the sub-goal will be to establish a rapport in order to obtain the main goal.  Takeo Doi in his study of consciousness distinguished this as tutemae, meaning conventions and verbal expressions and honne, meaning true motive behind the conventions.