This document discusses different types of viscometers used to measure viscosity. It defines viscosity and explains that viscometers measure it under various flow conditions. The main types described are rotational, vibrational, oscillation, falling piston, falling sphere, and Saybolt viscometers. Rotational viscometers measure viscosity under different conditions for Newtonian and non-Newtonian fluids. Vibrational viscometers continuously measure viscosity in pipes and tanks, while oscillation viscometers adapt laboratory and high-pressure/temperature measurements. Falling piston viscometers use a piston-cylinder assembly to draw fluid through a gap. Falling sphere and Saybolt viscometers also measure viscosity based on fluid flow properties.