There are three types of OSPF areas:
1. Standard area or area 0 (backbone area): This is the main area of the network and all other areas must connect to it. It is responsible for flooding LSAs throughout the network.
1. Stub area: This area is used to simplify routing and reduce overhead. It has no external routes and a default route is used to reach networks outside the area.
1. Totally stubby area: This is similar to a stub area, but it also blocks external routes from entering the area. Instead, it uses a default route to reach networks outside the area.
