ORMs are great for Rapid Application Development. You can get started very quickly. The price you pay is the vast complexity they hide under the hood. As your system grows, that complexity can bite you if you are not careful enough. Moreover, ORM packages create heavy objects that can make your life hard when doing batch processing. Knowing the basic principles and challenges when mapping an object to a relational database is a great blessing. This knowledge will help you make some important decisions as your application grows. by Alexandros Gougousis