This allows for major performance increase. If you span your website across multiple locations, not only are you provided fault tolerance, but you offer the best speeds for all your customers across the world as they will hit the closest server located by them.
Region & Number of Availability Zones
Oregon (3), Northern California (3)
Northern Virginia (5), Ohio (3)
São Paulo (3)
Ireland (3), Frankfurt (2), London (2)
Singapore (2), Sydney (3), Tokyo (3), Seoul (2), Mumbai (2)
New Region (coming soon)