How to Write a Software Design Document

Your idea and the idea's layout can be translated using a Software Design Document, the literal form of your idea, to help developers accurately design and program the applications to your specifications.

Before you sit down to write the document, take these tips into consideration.

Industry Terminology

The software developer probably doesn't know your industry well, but that doesn't mean the they can't create the application. To help the programmer understand your overall idea goals, it helps to explain standard industry terminology.

In your design document, dedicate a chapter to common terms with associated explanation. A chapter with terms helps the developer understand common acronyms and words used in each part of the application.

Database Model

Although you might not be able to write a database model, you can categorize the data you need stored in the application. For instance, you probably need to store customer data. Create a table in the design document that lists each piece of information you need to collect from customers. If you can accurately segment each section of the application, the developers can take the information and use it to design the database tables.

Typically, you can segment data collection by creating tables for each screen in the application. For instance, customer information is one screen, order data is another screen, and a list of products and product information is yet another screen. You can take each one of these screens and create a table of data you want to collect in the application.

Screen Wireframes

Wireframes are a simple representation of each screen and how you would like that screen presented on the user's computer. This section of the design document shows the developer where to place the logo, the menu and any layout for content and images. A wireframe doesn't need to have graphics or specific content.

It just needs to give the developer an idea of where each element should be displayed on the page. Wireframes also help the graphics designer determine how you want to lay out your main website design.

Workflow: Logic Graph and Usability Layout

After you have the model, wireframes, and industry terminology laid out, you need to tie those elements together. This is accomplished in a logic graph and usability layout.

For instance, what happens when the user clicks the "Buy Now" button? Does the application ask for customer information first, or does it navigate to an order page with a list of products?

These small details are laid out in a graph that specifies the workflow for the application. Depending on the project, some developers will take your design document and create a more detailed, technical document. 

The way you communicate your design to the developer greatly increases the success of the overall product, and it helps keep an accurate completion date for the project.

Create a great design document, and you won't need to make too many corrections at the end of the project.