APM (application performance monitoring) refers to a familiy of products that aims to monitor application performance from end to end, also from the customer perspective. While traditional monitoring solutions focuses on Exceptions and standalone technical metrics (e.g. error tracking, slow server endpoints, etc), in real world our app might create disappointed users without any code exceptions, for example if some middleware service performed real slow. APM products measure the user experience from end to end, for example, given a system that encompass frontend UI and multiple distributed services – some APM products can tell how fast a transaction that spans multiple tiers last. It can tell whether the user experience is solid and point to the problem. This attractive offering comes with a relatively high price tag hence it’s recommended for large-scale and complex products that require to go beyond straightforwd monitoring.