He or she will also choose the plugins for functionality and compatibility. Some server side technologies are vital in the functionality of websites, such as MySQL databases and CRON jobs.
Web development is the nuts and bolts side of the business. The designer has a vision of how the site will look, and the developer will make the pieces fit together and function.
WordPress can be customised and developed by using WordPress hooks which can place content in various locations around a page. I use hooks as well as custom posts and custom fields to produce a unique website.
I have some free and premium plugins that I use in almost every WordPress install when I build a website.
I will research the best WordPress plugin for some unique functionality that the client may require.