Choosing a database for your Node.js app can be challenging due to the many options available. Node.js supports both relational and non-relational databases, each with its own strengths and weaknesses. Relational databases are suitable for transactional-oriented applications such as e-commerce, while NoSQL databases are better suited for applications that require horizontal scalability. To connect a database to your Node.js app, a database driver or Data API is typically used, and package management tools like npm can simplify the process. With the rise of serverless architectures, Node.js provides an ideal environment for building scalable and efficient applications.