Makes a fact in the case more or less probable (likely)
That fact is "of consequence" (is valuable) in determining whether the action (in this case, negligence) occurred
NOTE: you need both of these elements in order for evidence to be considered relevant; however, most of the time direct examinations start with where the witness is from and what they do for a living. The judge will usually let that slide, so don't bother objecting to that
Duty of care
Breach of that duty
Harm
Causation