Oura is a Finnish technology company that produces a wearable ring that tracks sleep and activity. The ring uses infrared light sensors to measure the user's heart rate, heart rate variability, body temperature, and movement. The data is then analyzed by the accompanying app to provide insights into the user's sleep quality and activity levels. The company was founded in 2013 and has since raised over $48 million in funding. Its products are sold in over 100 countries.