This book explains the basics of Component based systems. It gives an insight about the component, component based development, and quality aspects in general for component based systems. It also compares various features of technologies namely .NET and JavaBeans components. It also discusses various quality attributes for component based systems like maintainability, reusability, complexity and others. It also explains several quality models like ISO 9126 and CMM. It also inform about various available metrics for component based systems. The main emphasis is on reusability, customizability and complexity related metrics. These metrics are classified as validated metrics on some existing component models or as metrics, which need to be validated and also proposes a new quality model for Component-based systems after making some modification in ISO9126 model. It adds some of the quality attributes like reusability, complexity and removes analyzability from the model. It also suggests the future work. And also proposes a Artificial Neural Network based approach for predicting maintainability of component based systems. It identifies the factors that influence the maintainability.