The increasing availability of COTS (commercial-off-the-shelf) components in the market of software development has concretized the opportunity of building whole systems based on previously built components. Component-Based Software Engineering (CBSE) is an approach which is used to improve efficiency and productivity of software system with the help of reusability. CBSE approach improves software development productivity and software quality by selecting pre-existing software components. Reusability in Component-Based Software Development (CBSD) not only reduces the time to market in development but also brings the cost down of development heavily. This paper represents the challenges which are faced by software developer during component selection like reliability, time, components size, fault tolerance, performance, components functionality and components compatibility. This paper also summarizes algorithms used for component retrieval according to availability of component subset.