Some of the common question engineers have around monitoring are, “Why should I monitor my service?”, “How do I monitor my service?” and “What tools do I use to do this?”. In this talk we will go through some of the key reasons for us to monitor our services and systems. We will then see some methods like the USE(Utilisation, Saturation and Error) and RED(Rate Error Duration) methods that help us identify what to monitor in a consistent manner. Lastly, we will cover some broad classification of tools that help us achieve this including some real examples of monitoring some systems and services at the Financial Times.