For many of us, rheology is the science that deals with the characteristics of flow. For some of us it is a word that is difficult to say and spell. To describe rheology as simple as possible, it is the ability of a material to flow and the resistance there is to this flow. All materials in nature, even solids, have the ability to flow. That is correct, solids can flow - we just have trouble seeing this flow. But for the most part, we are familiar with the following, most common types of flow. Rheology is best represented by fluid motion. Most people when they think of rheology, they first think of viscosity. The two terms are very closely related, but they are slightly different. Simply, rheology is a property of different types of materials while viscosity is a difference measurement of the flow of materials. They different types of materials can be explained as follows.
A Newtonian Fluid is one that will continue to flow no matter what forces are exerted on it. Water is best example of a Newtonian Fluid.