Monitoring applications in production requires effective logging to track activities and diagnose issues. Logging libraries in Go, such as Zap, Zerolog, Slog, apex/log, and Logrus, offer structured logging with features like severity levels, timestamps, and machine-readable formats such as JSON. Zap, developed by Uber, emphasizes performance and customization, while Zerolog provides high speed and a simple API. Slog, a recent addition to Go's standard library, supports structured logging and multiple formats. Apex/log offers flexibility in message formatting and destination forwarding, and Logrus, though in maintenance mode, remains a compatible option with structured logging support. Each library caters to different needs, and while Zap is recommended for immediate use, Slog is gaining traction as it integrates into Go's core library.