The energy consumption of every home is rising at alarming level, leading toincreased carbon footprint per person. To generate more electricity, more and morefossil fuels are burned causing bigger problems like climate change and othercatastrophic environmental damages. At the same time, wearable and mobile devicesare more common among the people than ever. With advancements in wireless technologies and computational power, many new technological breakthroughs have taken place over the last decade. The Indoor localization-based service is one of them. In this paper, various applications across several fields are explored, while walking through the available technologies of Indoor positioningsystems(IPS), the architecture, and algorithms. The evaluation metrics of Indoor Positioning is also discussed briefly.