For the average webmaster, design and development are words that are most often associated with the overall character of a website. How it looks, how it presents itself to the viewer, how it will adapt to future “design” changes. 

Of course, if your primary objective is to earn money online, the concept of design and development has a slightly different (and much less flamboyant) meaning. The design factor merely relates to simplicity and function. Basically, you want a viewer to be able to interact with the website in an efficient and effective manner.