Different kinds of system components including hardware elements, software algorithms, network connections, and sensors are required to cooperate with each other to provide various services in smart home. With the development of smart grid providing a two-way communication infrastructure, residents have the opportunity to schedule their electricity usage pattern to reduce their electricity cost. The energy management of a household level must take into consideration how to reduce the environmental burden, while supporting human's life style. The incentive and motivation to manage energy at the household level is influenced by commercial and technical reasons. Commercially, it offers the passive residential customer to be active in the energy market. The technical aspects include peak shaving, valley filling, load shifting, flexible load curve, strategic conservation and strategic load growth. Another important aspect of energy management systems is the socio-economic impact of such system. This paper reviews the concept of energy management systems for residential customers and looks into the background of smart home energy management system technologies. It highlights the major components, and comparatively analyzes various technological approaches. It also discusses some of the concerns and challenges such as cost, implementation and privacy issues of smart technologies.