Summarize the following:
Set up your letter as a standard business letter. Choose a font that is readable, such as Times New Roman 12 point.  Your boss should have told you who to address the letter to. If you don’t know, then call Human Resources to check. Don’t delay writing the letter. You should draft it as soon as you tell your boss. In the first sentence, you should state that you are leaving and identify your last day. You don’t want the give the impression that you’re open to a counter-offer or other negotiations to keep you with the company. For example, you can write, “I hereby resign as marketing assistant at ABC Corporation, effective May 22, 2017.” Even if you’re writing the letter to Human Resources, you should thank the company. This letter will go in your personnel file, and you don’t want to come across as ungrateful. You can thank your boss for hiring you and for anything else that you’re genuinely grateful for. For example, you can write, “I can’t thank you enough for hiring me nine months ago as your marketing assistant. This job allowed me to put my college education immediately to work, while teaching me more than four years of college ever could.” There might be negative comments or performance evaluations in your personnel file. Now is the time to correct the record by providing context.  For example, if you’ve been criticized in the past for being tardy, you can subtly explain why. You can write something like, “This company has been incredibly understanding. Even when I was going through chemotherapy and missing some time at work, I still managed to finish all of my work, thanks to the thoughtful staff at ABC Corp.” Remember to keep it brief and professional. You shouldn’t give a long-winded defense in which you go point-by-point and rebut every criticism ever made of you. Instead, explain away one or two of the major criticisms. Repeat how grateful you are for having had the chance of working the job, and then give the company your warmest regards. Also let the company know whether you’re open to them contacting you with questions. If you are, provide your phone number and email address. For example, you can write, “Thanks again for the nine months to learn and grow with this company. I wouldn’t be where I am today without the help of my direct supervisor, Greg Jones, and my co-workers Caron Smith and Abbi Johnson.” Make a copy of the letter for your records and then hand deliver it to Human Resources. You should also give your boss a copy of the letter so that they can read what you have written.

Summary:
Format your letter. Get to the point. Express gratitude. Set the record straight. End the letter warmly. Distribute the letter.