Fluentd is an open source data collector that unifies logging infrastructure by collecting, filtering, buffering, and outputting logs across multiple sources and destinations. It has a flexible plugin system, minimal resources required, built-in reliability, and can be integrated with Datadog for monitoring and visualization. The integration allows users to monitor Fluentd's performance as well as over 100 other applications and components, providing insights into site performance, customer behavior, and gnarly bugs that can help accelerate growth by learning more from data faster.