In the web design world, there is usually a web designer who creates the look and feel of the website and a web developer that take the wireframes and prototypes from the designers and execute them.
Then some people are known as both a web designer and web developer. These are hybrid designer/developers, the unicorn of the web world.
First, to fully understand what a hybrid designer/developer can do. We first have to understand what web designers and web developers do.
A web designer understands the needs of the user and focuses on the visuals of the website. They focus on what the user sees and interacts with, this is UX (user experience) and UI (user interface) are focused fields of web design.
A web designer focuses on creating user personas, usability tests, wireframe and prototypes to ensure that the website will flow and solve the intended problems.
A hybrid designer/developer can do both the jobs of a designer and developer. They can create a website effectively from start to finish. They start by creating wireframes and analyzing the features and layout that will be the best for the user. Then they can execute and develop the website.
A hybrid designer/developer will not be an expert in either web designer or web development. Their skills will be well rounded to accommodate projects that require versatility. They can complete projects for companies that may not have a large budget.
They are knowledgeable in both best design practices and best development practices. These are excellent skills to have to understand the process a website goes through entirely. These skills enable them to acknowledge browser limitations, saving time and effort and reducing disappointment during the initial design process. Accepting their limitations allows them to be creative in these restrictions to push the boundaries and execute both innovative and functional designs.