Building a website involves two main stages: Website Design and Website Development.
Website Design is essentially the process of sitting down, working out what you require for your website, and then designing the visual and graphical look of the site.
The design of the website will influence the building (or development) of the site. This includes the website structure, appearance of the web pages, functionality and so on. Therefore, it is critical to get this phase right.
When the Website Design is completed you will have a large picture of how your website will look including the visual design and requirements. The next step is Website Development.