Ubiquitous Computing is all about how people can interact with heterogeneous devices such as computer, mobile, Personal Digital Assistants (PDAs), tabs, small sensors without explicitly instructing these gadgets and few of such gadgets are invisible to the user. Ubiquitous computing is all about to make a computer so implanted, so appropriate and so natural which fulfil every requirement of the user what he/she is desired of. It provides more facilities to make people life easy and more comfortable due to intelligent sensor environment. Intelligent sensors work similar to the working of human being to accomplish a specific task. Ubiquitous Computing mainly deals with intelligent sensors, which are sometimes also known as ubiquitous sensors. Fundamentally Ubiquitous Computing involves four most important notions which are Context Awareness, Natural Interaction, Nano-Technology and Wireless Technology. In this paper we emphasis on exploring the ubiquitous computing architecture and intelligent sensor, which is the major fundamental component of ubiquitous computing. We have discussed Ubiquitous Intelligent Sensor Network Architecture and with this also emphasized on the applications of ubiquitous computing in various arenas.