What defining feature does a log have in relation to an event?

A log is a detailed record that captures the sequence of steps and actions taken during an event. It provides a comprehensive breakdown of what occurred, often including timestamps, messages, and other contextual information. This thorough documentation is crucial for troubleshooting and understanding system behavior, as it allows users to trace back through the event's process and identify where things went right or wrong.

In contrast, the other choices offer representations that do not align with the direct nature of a log. A summarization or a third-party synopsis would not provide the level of detail found in a log. Meanwhile, an abstract representation only captures outcomes without the procedural insights that logs convey. Additionally, referring to it as a temporary recording device diminishes its nature as a permanent record for analysis and audit purposes. Thus, the chosen answer accurately reflects the primary functionality of logs in relation to events.