Letter dismissing at the end of a probation period

What's a letter dismissing at the end of a probation period, and when do you need it?

You should use this letter when you do not want to keep on an employee at the end of their probation period and you intend to dismiss them.

Make sure that these reasons are factual, related to performance, and that there are no known factors that might explain why the employee’s performance during the probation period has been less than satisfactory.