What is the purpose of the Chorus in this play?

Shakespeare uses the Chorus to keep the audience up to date on developments in the storyline, as well as for apologizing for the limitations of trying to show these huge events on a tiny, wooden stage:

"Think when we talk of horses, that you see them
Printing their proud hoofs i' the receiving earth;
For 'tis your thoughts that now must deck our kings,
Carry them here and there; jumping o'er times,
Turning the accomplishment of many years
Into an hour-glass: for the which supply,
Admit me Chorus to this history;
Who prologue-like your humble patience pray,
Gently to hear, kindly to judge, our play." (Act I, Prologue)