Vibration measurement technology is less than 100 years old. It started with sensing earthquakes and aerospace applications. In machines, vibration measurements are important from their condition monitoring point of view and also for controlling their vibrations. There are both contact and noncontact types of vibration measuring systems available. Basically, the measuring system consists of a transducer, a signal conditioner, and a display (analog or digital) to display the vibration level. Vibration transducers giving signal output proportional to vibration acceleration, velocity, or displacement are used. The working of accelerometers, velometer (and laser-based instruments), different types of proximity probes, and LVDT is described. They all have their advantages and limitations and are to be selected as per the application. It is also useful to get a frequency spectrum of the vibration signal giving information about the frequency contents of the vibrating object. This information is obtained with the help of FFT analyzers and is required for monitoring the condition of machines as well as for vibration control work. Theory behind these analyzers and details of facilities provided in them have been covered. Finally, instrumentation for modal testing to obtain natural frequencies of structures is described.