Besides logs, an application can also emit one or more metrics. A metric is a series of values over time that describes one or more aspects of a system. Some examples of metrics are as follows:

• The number of users currently logged in
• The number of products viewed by users
• The number of database transactions

Gathering metrics such as these can provide insight into how a system is used and how it currently operates. Metrics are often used for creating dashboards and alerts.