For example, in marketplaces such as eBay or Taobao, buyers and sellers are the two groups. Buyers prefer a large number of sellers, and, meanwhile, sellers prefer a large number of buyers, such that the members in one group can easily find their trading partners from the other group. Therefore, the cross-side network effect is positive. On the other hand, a large number of sellers mean severe competition among sellers. Therefore, the same-side network effect is negative. "Figure 1" depicts these relationships.