Formal
To someone you have not met, whose name you don’t know Start- Dear Sir/Madam, End- Yours faithfully,
Semi-formal
To someone you may or may not have met, whose last name you know Dear Mr Brown,
Eg Start- End- Yours sincerely,
Informal
To someone you know well, whose first name you know and use Start- Dear John, Dear Anita, End- Best regards, Warm wishes,
EXAMPLE.
FORMAL LETTER.
You have received a letter from your university, The University of Cambridge, demanding a reason for your absence from an exam. You were ill that day, but failed to submit the evidence. Write a letter to the examinations committee explaining your situation. You should include:
- Apologies for the situation
- Identification for yourself (name, student number, case number)
- An explanation of what had happened and any possible evidence you may have
- Possible resolutions to consider.

TASK RESPONSE.
To the University of Cambridge examinations committee,
I am writing in response to your letter regarding my unauthorised absence from the mathematics examination held on the 24th September, case number M2342.
My name is Thierry Don, Student Identification Number S-4554. First off, let me render my apology for failure to inform the university in advance that I would not be able to attend.
On that sad day, for the first time in my life, I woke up with a splitting headache. I made a beeline to the hospital thinking I would be in time to attend. I however was informed by the doctor that my situation was worse than I had thought and it was by luck I managed to make it to the hospital. I was diagnosed with tension-type headache that caused tenderness of the face, head, neck, and shoulders, a feeling of pressure behind the eyes and sensitivity to light and sound. I this case, I could not leave hospital and was placed in the emergency unit section.
I do sincerely wish the committee can accept my request and reschedule my exam appointment two weeks from now as I am now getting better each day.
I once again apologize for the inconvenience I might have caused the committee.
Yours faithfully,
Mark Doran
(213 WORDS)