Rules of a business letter:

1. Address Heading: This is the writer’s full address. Business letters usually have preprinted, letterhead stationery which contains this information. An address heading is optional for informal letters.
   
   • Your address (Addressee´s data or Sender´s data): The return address should be written in the top right-hand corner of the letter.
   • The address of the person you are writing to (Addresser´s data): The inside address should be written on the left, starting below your address.
2. Date: this is the month, day and year that the letter is written on. e.g.: 4^th August 2021 or 4^th August, 2021.
   
   • Different people put the date on different sides of the page. You can write this on the right or the left on the line after the address you are writing to. Write the month as a word.
3. Inside Address: The recipient’s full name and address. Generally, informal letters do not include an inside address. 
   *Note:  Refer to Addressing Persons of Title when writing letters to these people.
4. Attention line (optional): With formal letters, the "Attention or For the attention of: [full name of recipient]" is placed two vertical spaces below the inside address. E.g.: For the attention of Ms. Potter.
5. Greeting: Also known as the “salutation,” this is the introductory phrase, “Dear [name of recipient].” Either a comma or a colon can be used at the end of this phrase. Today, a comma is more extensively used, with the exception of the use of a title (i.e. “Dear Member:”) and not a proper name. In this case, the use of a colon would be more appropriate.
   
   • Dear Sir or Madam,If you do not know the name of the person you are writing to, use this. It is always advisable to try to find out a name.
   • Dear Mr. Jenkins,If you know the name, use the title (Mr, Mrs, or Ms, Dr, etc.) and the surname only. If you are writing to a woman and do not know if she uses Mrs or Miss, you can use Ms, which is for married and single women.
6. Subject line (optional): A word or phrase to indicate the main subject of the letter, which is preceded by the word “Subject:” or “Re:” (Latin for “matter”). Subject lines may be emphasized by underlining, using bold font or all capital letters.  They can be alternatively located directly below the "inside address," before the "greeting."  Informal or social letters rarely include a subject line.
7. Body of the Letter: The complete text of the letter; the subject matter content.
8. Closing or ending a letter or complimentary close:: This is the farewell phrase or word that precedes the signature and is followed by a comma.  Closing should reflect a type of farewell or goodbye as the writer signs off.  Examples:  “Yours truly,” “Sincerely,” “Respectfully yours,” “Regards,” etc.
   
   • FORMAL: Yours sincerely (UK) / Yours truly (USA): If you know the name of the person, end the letter this way.
     • Yours faithfully: If you do not know the name of the person, end the letter this way.
   • INFORMAL: Sincerely, Yours, With best wishes.
   • Your signature: Sign your name, then print it underneath the signature. If you think the person you are writing to might not know whether you are male of female, put you title in brackets after your name.
     • *Note: "Thank you," is not considered an appropriate closing for a formal or business letter.  
9. Signature:
   The signed name of the writer. 
10. Identification Line:
    Formal or business letters include the full name of the writer printed below the signed name (two vertical spaces below the Closing).  It includes the writer’s professional designations and title with the organization.  Directly below that, the name of the organization which the writer represents.
11. Postscript:
    Is a brief sentence or paragraph introduced by the initials, “P.S.” (post scriptus) - Latin for “after having been written.”  It implies that the writer, having completed and signed the letter, had an after-thought.  Although this is still commonly used in informal letters, it is not widely accepted for use in formal or business letters.
12. <div style="width: 100%;"><div style="position: relative; padding-bottom: 120.00%; padding-top: 0; height: 0;"><iframe frameborder="0" width="250px" height="300px" style="position: absolute; top: 0; left: 0; width: 100%; height: 100%;" src="https://view.genial.ly/5f04d3883d3a380d79e10e11" type="text/html" allowscriptaccess="always" allowfullscreen="true" scrolling="yes" allownetworking="all"></iframe> </div> </div>Notation:
    Part of a formal or business letter consisting of brief words or abbreviations as notations.

Examples:

• “R.S.V.P.” (Répondez s’il vous plaît) - French for “Please reply.”
  The use of this notation indicates that the writer expects the recipient to contact the writer with a “yes” or “no” response to the invitation extended in the body of the letter.  Often a corresponding address and/or phone number is printed directly below this notation.
• “CC:” (carbon copy) - These initials are followed by a name or column of names, indicating those people to whom a copy of the letter is being sent to.  (One-sided inked carbon paper slipped between two pieces of paper was once the method used for duplicating copies of correspondence, hence use of the word "carbon" in this notation).
• “encl.” (enclosure) - Indicates that something else accompanying the letter is enclosed.
• “PL/rm” (initials of persons) - Indicates that a person typed or even composed a letter on behalf of someone else. The capitalized initials are those of the sender of the letter (Paul Lazarman). The lower-case initials are those of the person who typed or composed the letter (Rachel McDonald) on behalf of the sender. The most common use for this notation is for situations where an administrative assistant composed and/or typed the final version of a letter that was dictated by his/her boss.