In the 1970s, researcher Mark Granovetter investigated the best methods for job seekers to achieve employment. Typical strategies were job application in response to an ad, contacting friends and relatives, and contacting acquaintances both in business and social circles. Although the expression "it's who you know," carries the connotation of who you know well, Granovetter's research demonstrated that the best contacts are those you don't know well.

Granovetter called his famous article The Strength of Weak Ties, referring to the power of networking with acquaintances.

Acquaintances and colleagues provide the weak associations through which we gain access to new opportunities. Close friends cannot provide many new outlets; they are constrained in the same spheres as the job seeker. Granovetter did not rule out the value of friendships, nor the practicality of submitting employment applications where no prior contact existed. He just documented that these were not the most likely pathways to employment.

Research into how connections are made in groups cross culture as well as discipline. Social psychologist John Turner of Australia suggested how humans interact in groups in his Group Identity Theory. Anthropologist Robin Dunbar posited that humans can manage well in groups up to 150, meaning that they can keep track of all group participants and care about how the group gets along ("Dunbar's Number"). Related to the discussion is the Small World Experiment by one of America's most famous social psychologists, Stanley Milgram. Milgram established that humans can communicate quickly through social networks, and the work has continued to be tested in the so-called Six Degrees of Separation experiments.

Social network theory today must also address the connections afforded by the Internet and similar electronic communications.

Search terms for follow-up investigation: Mark Granovetter, Robin Dunbar, Stanley Milgram, social networks