Purpose: Pulse oximetry is a noninvasive medical technique that measures the amount of oxygen in a person's blood by shining light through their skin. It is widely used in medical care and is considered as important as the 4 traditional vital signs. In this article, it was aimed to review all aspects of pulse oximetry in detail. Materials and Methods: The international and national reliable sources were used in the literature review for critical data analysis. A total of 13 articles including 9 reviews, 1 comparative clinical research, 1 cost-saving quality improvement project, 1 cross-sectional and multicenter descriptive study, and 1 questionnaire study were used for the preparation of this part of the review. Results: The history, principles, advantages, limitations inaccuracies, cost analysis, the level of knowledge about pulse oximeter among clinicians, and pulse oximetry versus tissue oximetry were all reviewed in detail. Conclusion: The device has a significant impact on modern medicine, allowing continuous monitoring of hemoglobin oxygen saturation in arterial blood. Oximeters are valuable in managing oxygen levels in respiratory and nonrespiratory diseases and have become an essential tool in hospital settings. Detecting low levels of oxygen saturation early can alert patients to seek medical attention promptly. It is crucial to comprehend the working and limitations of pulse oximetry technology to ensure patient safety.