Business memos are an internal form of communication used to deliver information or instructions. They originate from the Latin word "memorandus," meaning to be remembered. Effective memos focus on a single topic so the reader can quickly understand the message. While memos can save time and maintain good relationships, they also carry disadvantages such as being time consuming, expensive, and lacking formality or explanation at times. Common types of memos include directive, trip report, response, and field report memos.