Abstract
Networks portray a multitude of interactions through which people meet, ideas are spread, and infectious diseases and malicious rumors propagate within a society. Recently, researchers have found that unsolicited malicious attacks spread extremely fast through influential spreaders. For example, in April 23, 2013, the twitter account of Associated Press was hacked to spread the rumor that explosions at White House injured Obama. This led to both the DOW Jones industrial average and Standard & Poor’s 500 Index plunging about 1% before regaining their losses. Hence, identifying the most efficient ‘spreaders’ in a network becomes an important step towards restraining spread of malicious attacks. In this chapter, we investigate the methods of measuring influence of network nodes.