The document discusses the components and purpose of an effective sales letter. It explains that a sales letter aims to generate sales or support for a product by convincing the reader to take a specific action like placing an order or requesting more information. It outlines the AIDA model for composing sales letters, which stands for Attention, Interest, Desire, and Action. The letter should first catch the reader's attention, then build their interest and desire for the product using benefits and evidence, and finally provide a clear call to action for the reader to purchase or engage further. Examples are given for each AIDA component to illustrate how to craft a persuasive sales message.