This lecture introduces the fundamental principles of measurement systems, focusing on their structure and components. A measurement system typically consists of three main elements: the sensing element, the signal conditioning element, and the signal presentation element. The sensing element interacts directly with the physical variable, while the signal conditioning element processes the signal to make it suitable for interpretation. Examples of signal conditioning include amplifiers and analog-to-digital converters. The lecture also discusses measurement accuracy, uncertainty, and the importance of calibration procedures. Various types of measurement systems, such as thermometers and thermocouples, are examined to illustrate these concepts. The lecture emphasizes the significance of understanding measurement errors, which can be classified into gross errors, systematic errors, and random errors. The distinction between precision and accuracy is highlighted, explaining how a precise measurement system may not always be accurate. Overall, this lecture provides a comprehensive overview of the principles that govern measurement techniques in engineering applications.