Modern day application development is a multifaceted process that demands a team with a strong and diverse skill set. Regardless of team size, there are many roles in the development environment. The responsibilities are typically broken down into two categories, namely the client side and the server side.
By comparison, the server-side logic is backend development. A backend developer may know very little about HTML or CSS, but they will know how to satisfy the requirements required for the front end.
The article is about backend development, and how to hire the right person for your server-side programming. This involves a particular set of skills that range from low-level algorithm design to higher level database work, and although it will vary between projects there are core aspects that will not change.