This document discusses using Amazon Elastic MapReduce (EMR) for cost-effective big data processing. It describes the author's experience using EMR to process 1TB of log data per week for a startup. Key advantages of EMR include only paying for usage, no hardware to maintain, and ability to customize cluster resources for different jobs. The author outlines best practices learned, such as splitting logs by type and processing in smaller windows, as well as next steps like using spot instances and NoSQL for improved performance and cost savings.