Letters/Emails can be formal, informal, semi - formal or informal depending on who we are writing to.
Reasons for writing include: giving news, invitations, complaining, expressing apology, etc.

General Outline

Greeting - Paragraph 1 ( opening remarks, reasons for writing) - Paragraph 2, 3 - development of the topic - Paragraph 4 - closing remarks - sign off

Informal style

Greeting: Dear John/uncle/mum
- friendly, personal style (e.g.: Thanks so much for your last letter.)
- frequent use of colloquial expressions, idioms, phrasal verbs, short verb forms (e.g.: It's been ages since we last saw each other.)
- pronouns are often omitted (e.g.: Thought I'd drop you a line.)
- chatty language (e.g. I hope you're doing well.)
- simple linking words (e.g.: and, but, so.)
Sign off: Best wishes/ Yours/ Regards (our first name)

Semi - formal style

Greeting: Dear Mr. Harris,
- polite tone (e.g. I would like to thank you for your help.)
- use of less colloquial language (e.g. Thank you so much for your letter, instead of Thanks a million for your letter.)
- less frequent use of short verb forms, linking words, phrasal verbs (e.g. Also, I was wondering if you had a computer I could use while I am staying with you. )
Sign off: Regards, /Kind regards, (our full name)

Formal style

Greeting: Dear Sir/Madam, Dear Mr. Smith
- serious, impersonal style (e.g. I was pleased to hear that you are in good health.)
- complex sentence structure - frequent use of passive voice - formal linking words - no colloquial English - advanced vocabulary - no short verb forms ( e.g. The item in question, which I received last week, was damaged in transit. I would be grateful if a replacement could be dispatched as soon as possible.)
Sign off: Yours faithfully, /Yours sincerely, (our full name).