Is there over-time pay or ways to earn extra money?
This depends on the company you work for, and whether you are an exempt or non-exempt employee. Exempt employees are paid a salary, which generally means that you are paid a fixed annual amount regardless of how much you work. Exempt employees are usually more senior. Compensation policies for non-exempt employees vary from company to company. At NASA, engineers are compensated for any extra hours we work by banking them as either “credit time” or “compensatory time”, and we take these hours as vacation later on.
