In this paper we assume that time synchronized measurements will be ubiquitously available at all high-voltage substations at very high rates. We examine how this information can be utilized more effectively for real-time operation as well as for subsequent decision making. This new information available in real time is different, both in quality and in quantity, than the real-time measurements available today. The promise of new and improved applications to operate the power system more reliably and efficiently has been recognized but is still in conceptual stages. Also, the present system to handle this real-time data has been recognized to be inadequate but even conceptual designs of such infrastructure needed to store and communicate the data are in their infancy. In this paper, we first suggest the requirements for an information infrastructure to handle ubiquitous phasor measurements recognizing that the quantity and rate of data would make it impossible to store all the data centrally as done today. Then we discuss the new and improved applications, classified into two categories: one is the set of automatic wide-area controls and the other is the set of control center (EMS) functions with special attention to the state estimator. Finally, given that the availability of phasor measurements will grow over time, the path for smooth transition from present-day systems and applications to those discussed here is delineated.