A nursing care plan has five key components: nursing diagnosis, expected outcome, nursing interventions and rationales, and evaluation. It is created through a five-step process: 1) assessment of subjective and objective data, 2) diagnosis, 3) determining outcomes and planning, 4) implementing interventions, and 5) evaluating outcomes. The care plan is updated constantly based on new patient data and aims to help patients achieve measurable goals within a specific timeframe through evidence-based nursing actions.