This guide provides an in-depth exploration of using Grok patterns with Logstash to parse and process various common log types such as those from Nginx, IIS, MongoDB, MySQL, AWS ELB, AWS ALB, AWS CloudFront, and Elasticsearch. It covers practical steps for configuring Logstash, including downloading necessary files, setting up Grok patterns, and using the Grok Debugger Tool to test patterns. The document emphasizes the flexibility of Grok patterns in extracting specific fields from log data and transforming them into structured formats for analysis. Additionally, it demonstrates handling multiline logs and mapping user agents and IP addresses to more human-readable forms, enhancing the utility of log data for troubleshooting, performance tuning, and security monitoring. The guide concludes with instructions for cleaning up resources and notes that slight modifications can adapt these patterns to different log configurations.