A probationary period is a set time in which an employer can terminate an employee at any time without cause, notice, or severance pay. Generally, at the end of a probationary period, the employer will review the employee's performance to determine if they continue employment as a regular employee.
Probationary periods allow employers time to determine if employees:
Can help accomplish the employer's goals
Have the necessary skills to perform the required tasks
Fit with the employer's work environment
Generally, once a probationary period ends, an employee qualifies for health and other benefits. In addition, once a probationary period ends, employers must have just cause to terminate an employee. In the United States, 90-day probationary periods are standard.