Ecommerce retailers are increasingly faced with challenges of finding ways to provide a seamless shopping experience to customers. In the first chapter of this dissertation, we focus on the checkout process and study the impact of adopting one-click buying, a feature that reduces the number of steps required to place a purchase order to a single click, on subsequent customer behavior. Using quasi-experimental data over a period of 35 months from an online retailer before and after the launch of one-click buying, we find adopting one-click buying is effective in lifting customer purchases and does so by making treated customers purchase more often as well as more items. The impact of adopting one-click buying on customer purchases post adoption is economically significant, persistent over time, and heterogeneous across customers. Analyzing clickstream data of customer activity online and purchases across product categories, we provide evidence that the increase in purchases is driven by richer engagement through both more visits to the website and more page views upon visit as well as the expansion of purchases across categories. We discuss the implications of our findings for customer experience and targeting. In the second chapter, we study the impact of online product sampling on customer behavior. Online product sampling offers customers the try-before-you-buy experience to overcome the shortcomings of information loss they experience when purchasing physical experience products such as food, beverages, and apparel in ecommerce. Using quasi-experimental data over a period of 13 months from a retailer before and after the launch of online product sampling, we find online product sampling is effective in lifting customer purchases and does so by making treated customers purchase more items per order. We find the impact of online product sampling on purchases post treatment is economically significant, persistent over time, and heterogeneous across customers. Furthermore, we find the impact spills over positively to brand demand and expands to both online and offline channels. We provide evidence that product sampling generates positive affect among treated consumers. In the third chapter, we study the impact of a policy change by Facebook, a major social media platform, on user behavior. Platform algorithms play an important role in the digital economy. They serve as gatekeepers in social media platforms because they determine visibility, sharing and flow of information. They also affect both intermediaries who publish content to generate traffics to their websites and users who engage to consume and share content on the platforms. Using data from a series of experiments conducted at a publisher's website over a period of 121 weeks before and after the policy change by Facebook on its algorithm, which aimed to improve user engagement, we find the policy change significantly affected user behavior. In particular, after the change went into effect, user engagement decreased significantly insofar as users made significantly fewer clicks on the publisher's website. Using Google search volume data, we provide evidence on the selection mechanism on users through which the policy change by Facebook affected users. We discuss the implications of our findings for platforms, intermediaries and users.