Short and plain is the right approach
A resignation letter does not need to be long. Your department, position, name, intended last day, and a concise reason are enough -- a lengthy explanation or anything that reads as a complaint tends to create unnecessary friction instead. This is general guidance, not legal or HR advice, so if your employer has its own required format or process, follow that first, and check specifics with your HR department.
Give verbal notice before submitting anything in writing
Telling your manager in person before handing over a written letter is considered good professional etiquette in most workplaces. It gives your manager a chance to react and plan without being surprised by a document, and it generally leads to a smoother, more amicable transition.
Frequently Asked Questions
Does my employer have to approve my resignation right away?
In most jurisdictions, a resignation generally takes effect after a set period once you have given notice, regardless of whether your employer formally approves it -- but the exact rule depends on your employment contract and local labor law, so it is worth confirming with HR.
Is it okay to submit a resignation letter by email?
Some employers accept email or an internal system submission, while others require a signed paper original, so it is safest to check with HR about the accepted submission method before sending anything.