Barrier to erosion consists of 4 things. The first one is IT – resource that is all about the asset and capabilities to produce and use the technology core. The second one is complementary. It is a way to add strategy into two or more resources which can substitute for one another and make them more leverage. For the third one, it is IT – resource this means the company has the unique strategy that has more complexity and other company can’t copy it easily. The last one is preemption barrier. This is the way to change old method into the new method directly. For example, changing method for sending and storage the data by using fax to be sending and storage by using cloud.