Tremendous growth in online consumer participation has facilitated new business models by firms trying to leverage User-Generated Content (UGC). As a type of the outcomes of UGC, social media is one of the fastest-growing media forms and may significantly affect firm's economic actions or performances. My dissertation investigates several important aspects of consumer's online behavior and the relationship between the behavior and firm's economic performance. The dissertation comprises three essays focusing on these aspects in consumer software sampling, informational cascading in online user product reviews, and the economic impact of online user product reviews on sales. [The dissertation citations contained here are published with the permission of ProQuest LLC. Further reproduction is prohibited without permission. Copies of dissertations may be obtained by Telephone (800) 1-800-521-0600. Web page: http://www.proquest.com/en-US/products/dissertations/individuals.shtml.]