A formal letter is a letter, written in formal language, in the stipulated format, for official purpose. A letter written in an friendly manner, to someone you are familiar with, is called informal letter. Written in prescribed format only. and then a semi formal letter is a letter similar to business letters: they are concise and informative.
Answer: A formal letter is done with strict etiquette and dignigfied to consitue it's importance to the given occasion. A sem-formal letter combines formal and infomal elements when it comes to the tone. Lastly, an inform letter is written to give facts on a situation ro notify them about spefic information.
