A resignation letter is a formal document submitted by an employee to inform their employer of the decision to leave the company. It generally includes a clear statement of resignation, the intended last working day, and optionally, a brief explanation for the departure. The letter often conveys appreciation for the opportunities and experiences gained during the tenure and may include an offer to help with the transition process. Signing the letter reflects professionalism and respect, and it serves as an important courtesy to provide the employer with sufficient notice and time to plan for the change.