This document discusses 10 types of business letters: 1) sales letters, which aim to capture interest and prompt action; 2) order letters, which contain product details and payment information; 3) complaint letters, which should use a professional tone; 4) adjustment letters, which respond to claims; 5) inquiry letters, which ask questions and request information; 6) follow-up letters, which thank or review outcomes; 7) recommendation letters, which describe a professional relationship; 8) acknowledgment letters, which confirm receipt; 9) cover letters, which describe enclosed materials; and 10) resignation letters, which provide notice and reasons for leaving. Effective business letters follow standard formats and serve specific communication purposes.