Small and medium-sized enterprises (SMEs; sometimes also small and medium enterprises) or small and medium-sized businesses (SMBs) are businesses whose personnel numbers fall below certain limits. The abbreviation “SME” is used in the European Union and by international organizations such as the World Bank, the United Nations and the World Trade Organization (WTO). Small enterprises outnumber large companies by a wide margin and also employ many more people. SMEs are also said to be responsible for driving innovation and competition in many economic sectors. Petrakis and Kostis (2012) explore the role of interpersonal trust and knowledge in the number of small and medium enterprises. They conclude that knowledge positively affects the number of SMEs, which in turn, positively affects interpersonal trust. Note that the empirical results indicate that interpersonal trust does not affect the number of SMEs. Therefore, although knowledge development can reinforce SMEs, trust becomes widespread in a society when the number of SMEs is greater.