ABSTRACT Reusable software components are designed to apply the power and benefit of reusable, interchangeable parts from other industries to the field of software construction .Benefits of component reuse such as sharing common code, and components one place and making easier and quicker. The most substantial benefits derive from a product line approach, where a common set of reusable software assets act as a base for subsequent similar products in a given functional domain. Component is fundamental unit of large scale software construction. Every component has an interface and an Implementation. The interface of a component is anything that is visible externally to the component. Everything else belongs to its implementation. This paper addresses the primary boundaries for software component reuse technology. Keywords Software Reuse, component, boundaries, interface, product. 1. INTRODUCTION 1.1 Software Reuse Software reuse is the process of creating software systems from existing software rather than building them from scratch [1]. Software reuse is still an emerging discipline. It appears in many different forms from horizontal reuse and vertical reuse to systematic reuse, and from white-box reuse to black-box reuse. Many different products for reuse range from ideas and algorithms to any documents that are created during the software life cycle [2].Source code is most commonly reused in software systems; thus many people misunderstands software reuse as the reuse of source code alone. Recently source code and design reuse have become popular with (object-oriented) class libraries, application frameworks, and design patterns. Software components provide a vehicle for planned and systematic reuse [2].