A ggplot developer uses the package in R programming language to create data visualizations. Their work involves making graphs, charts, and plots to represent complex data in a simpler, more understandable form. They adjust aesthetics like color and shape, add layers, scales, and themes, and manipulate data to fit on different coordinate systems. A ggplot developer also ensures the data's integrity by handling missing values and outliers. They play a crucial role in data analysis and interpretation, helping organizations make data-driven decisions. They should also have a good understanding of statistics and data science.