An employment offer letter is a written offer of a position with a company. The letter includes the terms and conditions of employment, which were most likely discussed in an interview prior to the letter.
The letter specifies the duties the offered position entails. It includes the employee's start date and the name of her supervisor. Salary and commission, if any, must also be included in the letter along with any other benefits offered to the employee, such as health insurance, vacation time and sick time. The offer letter is a starting point for negotiation about the terms of employment.