In a nutshell, a doctor’s letter is any document written and signed by a licensed medical professional. They are usually given to patients when they fall ill and will usually provide evidence that they are not currently fit to work, travel, etc.
The letter will usually contain information about a patient’s medical history, current health condition and/or treatment plan. A doctor’s letter can be used for a variety of purposes, such as to provide evidence of a medical condition or disability, to support a request for accommodations, or to certify that a patient is fit to travel or participate in certain activities.