# Session ## Session Attributes Session is defined as the period of time encompassing all activities performed by the application and the actions executed by the end user. Consequently, a Session is represented as a collection of Logs, Events, and Spans emitted by the Client Application throughout the Session's duration. Each Session is assigned a unique identifier, which is included as an attribute in the Logs, Events, and Spans generated during the Session's lifecycle. When a session reaches end of life, typically due to user inactivity or session timeout, a new session identifier will be assigned. The previous session identifier may be provided by the instrumentation so that telemetry backends can link the two sessions. | Attribute | Type | Description | Examples | Stability | |---|---|---|---|---| | `session.id` | string | A unique id to identify a session. | `00112233-4455-6677-8899-aabbccddeeff` |  | | `session.previous_id` | string | The previous `session.id` for this user, when known. | `00112233-4455-6677-8899-aabbccddeeff` |  |