wtf is jaeger?

Jaeger is an open-source tool that helps you see what's happening inside large, complex software systems made up of many interconnected services. When something goes wrong, or runs slowly, in a modern application, it's often hard to figure out why, because a single user request might travel through dozens of different services. Jaeger captures detailed information about each step of that journey and shows you a complete picture of what happened. Think of it like this: if your application is a busy restaurant with many stations (prep, cooking, plating, delivery), Jaeger records exactly which orders went where, how long each step took, and where bottlenecks occurred. You can use this information to spot performance problems, debug failures, understand how different services depend on each other, and optimize your system. The tool has three main pieces that work together. First, lightweight code in your application (using OpenTelemetry, which is the modern standard) sends trace data to a Jaeger collector. Second, the collector stores this data in a database, you can choose from several popular options like Cassandra, Elasticsearch, or others. Third, a web-based dashboard lets you search for and visualize traces, so you can investigate what went wrong and understand how your system behaves under load. Jaeger was originally created by Uber, who process billions of traces every day, and it's now maintained by the Cloud Native Computing Foundation. It's designed to scale from small development setups (with in-memory storage for testing) to massive production deployments running in Kubernetes. The project is mature, well-maintained, and used by many organizations. If you're running microservices and want visibility into how requests flow through your system, this is the kind of tool you'd reach for.