The term pervasive or ubiquitous stands for existing everywhere. The ubiquitous computing is a model of human computer interaction. Here the information processing has been thoroughly integrated into everyday objects and activities. This technology is also called as pervasive computing. All models of pervasive computing share a visualization of economical, robust networked processing devices. This model is advancement from the desktop paradigm. It is based on embedding microprocessors in real time objects so that they can easily communicate information. The pervasive computing mainly depends on the wireless technologies, Internet and the advanced electronics. The pervasive computing devices are completely connected and they always exist. The researchers create smart products for the communication. The products are connected to the Internet and they generate the data that is always available. This technology places challenges in many fields of computing science design and engineering, modeling and also in user interface design. The three basic forms for ubiquitous system devices are tabs, pads and boards. Three additional forms are dust, skin and clay. The tabs are the wearable centimeter sized devices. The pads are the hand-held decimeter sized devices. The boards are the meter sized interactive display devices. The practical application of pervasive computing is the replacement of old electric meters with smart meters.