who gave the concept of ingroup and outgroup
Ingroups and outgroups The terminology was made popular by Henri Tajfel and colleagues during his work in formulating social identity theory. The significance of ingroup and outgroup categorization was identified using a method called the minimal group paradigm. Tajfel and colleagues found that people can form self-preferencing ingroups within a matter of minutes and that such groups can form even on the basis of seemingly trivial characteristics, such as preferences for certain paintings.[1][2][3][4][5]
Triple Entente Historians continue to debate the importance of the alliance system as one of the causes of World War I. At the start of World War I in 1914, all three Triple Entente members entered it as Allies against the Central Powers: Germany and Austria-Hungary.[1]