Block Style
The letter below is a response to an inquiry, written on headed stationery in BLOCK STYLE. Notice how all the parts are even with the left margin (left justified) and there is no paragraph indentation. It contains the Main Parts and the Special Parts of a business letter.

Semi-block Style
The letter below is a response to an inquiry, written on headed stationery in SEMI-BLOCK STYLE. Notice the position of the date, the closing, and the signature and that the paragraphs of the body are indented 2-3 spaces. Note that the first paragraph is NOT indented. It contains the Main Parts and the Special Parts of a business letter.
