A metric is a collection of telemetry data that is visualized within the monitoring solution and provided in a monitoring dashboard.

In the area of metrics, we know two types and, according to the level of abstraction, five classifications.

Types of metrics are:

• Pre-defined or common metrics
• Custom metrics

What is the difference between these two types? While common metrics come in the context of general infrastructure elements (for example, to measure the CPU usage), custom metrics cover all user-defined measurement points.

Classifications of metrics are:

• Client metrics: Client metrics are concerned with measuring the perception of the end user, for example, how long does it take for a client application to process and render results? Other areas covered by client metrics are the responsiveness of local and remote operations, the memory footprint, and the CPU usage.
• Business metrics: Business metrics provide a viewpoint to the logical operations (all end user activities) that define the business process. In terms of best practice, business metrics should cover all business transactions that the system performs.
• Application metrics: Application metrics include all measurements of the activity and performance of the application layer (that is, the application code, all application frameworks, and runtime execution environments used by the application). The purpose of these metrics is to help you synchronize the flow through the application with a potentially large number of concurrent user requests, analyze the resources that are consumed, and evaluate the likelihood and causes of performance issues.
• System metrics: System metrics capture information about the performance of the underlying infrastructure. These metrics are typically focused on Key Performance Indicators (KPIs) associated with memory occupancy, network utilization, disk activity, and CPU use.
• Service metrics: Service metrics cover the performance of dependent services, such as Azure Storage, messaging, cache, database, and any other external services your application may use. However, these types of metrics do not measure the performance of these services themselves, but capture information about the performance of the queries your system sends to them.

Let's look again at the classifications in detail.