Henry IV: Part I is the second in a series of four English history plays that make up Shakespeare's major tetralogy. It continues the saga of the Bolingbrook family and the Plantagenet monarchy that begins with Henry IV's seizure of power in Richard II; it leads naturally to Henry IV: Part II; the tetralogy culminates in Henry V, as Prince Hal of Henry IV's reign becomes Henry V, the great and beloved warrior king of the English people. Quite obviously, Shakespeare drew upon chronicles of actual English history as the framework for Henry IV: Part I and the other three plays in the series. Just as clearly, the playwright compressed the timing of events for dramatic purposes and composed all of the play's dialogue.
But even more important, the "tavern" dimension of Henry IV: Part I is purely Shakespeare's creation. Its addition allows Shakespeare to use the dramatic techniques of juxtaposition, inversion, and antithesis as the plot shifts back and forth between the troubled realm of Henry IV's court and the madcap, vulgar world of the tavern in which Sir John Falstaff presides. Indeed, the counterpoint contrast between the high and the low that Shakespeare uses here was a radical stage innovation in its day, allowing for the inclusion of comic episodes within a deadly serious political history. At bottom, Henry IV: Part I is essentially a coming of age story in which the king's son, Prince Henry or Hal, emerges from his youthful role as a wastrel companion of the tavern crew, into the role of a genuine English monarch by virtue of both blood and character.