The document summarizes localization techniques for wireless sensor nodes. It discusses several common localization methods including known location-based using GPS, proximity-based using signal strength, angle-based using angle of arrival, and range-based using time of arrival or time difference of arrival. It also covers some challenges with each approach like accuracy limitations and environmental factors. Finally, it provides a brief comparison of the localization techniques and their typical accuracy ranges from 1-15 meters depending on the method.