Growth without observability is guesswork. Observability shines a light on what’s working, what’s not, and what to fix next. It’s how you know if your product is truly performing or just surviving.
It is the foundation of growth engineering because it answers the following questions:
Is our system healthy?
Are users even seeing our new, shiny feature?
How are users interacting with our product?
By monitoring observability data, we can refine user experiences, optimize performance, and run better experiments.
The concept of observability comes from control theory, where it was formally defined in the 1960s by Rudolf E. Kálmán, a pioneer in modern control systems.
His definition: “A system is observable if you can determine its internal state solely by examining its outputs over time.”1
In simpler terms, imagine a box you can’t open (Figure 2-1). Can you figure out what’s happening inside just by watching what comes out?
Figure 2-1: A simplified illustration of observability: the system is a box, but by capturing signals (charts, logs, events), the engineer can understand what’s happening inside.
This idea was essential for early autopilot systems, where engineers needed to infer an aircraft’s internal state (like pitch, velocity, or altitude) from sensor data without ever “opening” the plane.
As software became increasingly complex and distributed, ...
Become an O’Reilly member and get unlimited access to this title plus top books and audiobooks from O’Reilly and nearly 200 top publishers, thousands of courses curated by job role, 150+ live events each month, and much more.
O’Reilly covers everything we've got, with content to help us build a world-class technology community, upgrade the capabilities and competencies of our teams, and improve overall team performance as well as their engagement.
Julian F.
Head of Cybersecurity
I wanted to learn C and C++, but it didn't click for me until I picked up an O'Reilly book. When I went on the O’Reilly platform, I was astonished to find all the books there, plus live events and sandboxes so you could play around with the technology.
Addison B.
Field Engineer
I’ve been on the O’Reilly platform for more than eight years. I use a couple of learning platforms, but I'm on O'Reilly more than anybody else. When you're there, you start learning. I'm never disappointed.
Amir M.
Data Platform Tech Lead
I'm always learning. So when I got on to O'Reilly, I was like a kid in a candy store. There are playlists. There are answers. There's on-demand training. It's worth its weight in gold, in terms of what it allows me to do.
O’Reilly covers everything we've got, with content to help us build a world-class technology community, upgrade the capabilities and competencies of our teams, and improve overall team performance as well as their engagement.
