The primary focus of a machine learning engineer is to develop algorithms and models that enable computers to learn from data. This role involves selecting appropriate datasets, training models, and fine-tuning algorithms to improve performance and accuracy. Machine learning engineers work closely with data scientists to design solutions for various applications, such as natural language processing, image recognition, and prediction systems. Their expertise in programming, statistics, and data manipulation is crucial for building scalable models that can adapt to new data and improve over time.