What Is Top-Down Design?

A top-down design decomposes a system into smaller parts to comprehend its compositional sub-systems. It's like peeling an onion. You start with the outermost layer, then move through each one until you find the core that you do when you design with a top-down approach: You start by looking at the big picture and then work your way down to individual components. Top-down design is a method of software development that begins with the big picture and then works its way down to the details. The idea behind the top-down design is to start with a high-level overview of what you want your program to do. Then, you break up this overview into smaller and smaller parts until you have all the individual pieces you need to create your program. For example: Let's say you're building a website that allows people to buy books online. You might start by thinking about what people will do on your website: searching for books, viewing book details, buying books, etc. Then, once you've identified those tasks, you can take each one apart into smaller parts: searching for books might include searching by author name or title; viewing book details might consist of showing cover images and descriptions; buying books might involve allowing users to enter their credit card numbers and billing addresses; etc. This breakdown process could go on until only individual steps are left, for example, "click here" or "type this". At this point in the top-down design, nothing has been created, just a list of tasks that need to be accomplished. We've all heard, "A chain is only as strong as its weakest link." Well, that's not true anymore because now we have an entirely new way of building the chain! All you need to do is identify your base elements. Once you have these, you can build them into modules, which makes it easy to put them together and create your entire system.