"Facilitate onboarding and training" means that audit trails help new team members:

1. _Get up to speed quickly_: New team members can rapidly understand the project's history, context, and decisions.

2. _Understand the "why" behind changes_: New team members can see the rationale and justification for changes, reducing confusion.

3. _Learn from past experiences_: New team members can benefit from the team's collective knowledge and experiences.

4. _Integrate into the team more smoothly_: New team members feel more comfortable and prepared, reducing the onboarding curve.

5. _Make informed decisions faster_: With access to the project's history and context, new team members can make informed decisions more quickly.

6. _Reduce knowledge gaps_: New team members can fill knowledge gaps and understand the project's evolution.

7. _Improve collaboration and communication_: New team members can communicate effectively with the team, using shared knowledge and context.

8. _Enhance overall team efficiency_: The team's overall efficiency and productivity increase, as new members become productive faster.

By facilitating onboarding and training, audit trails enable new team members to hit the ground running, reducing the time and effort required to get up to speed.