 So, welcome to the lecture on properties of fluids. We will first see what is fluid, what is the basic fundamentals of fluid or what qualifies to be called as fluid. Let us apply this concept for solid liquids and gases and decide which one of them could be called as fluid. And as this is an introductory lecture, let us try to understand different engineering applications of fluids. So, before that let us try to understand what is a fluid, what is the definition of a fluid. Let us have a basic understanding through a small animation video which is meant for solid liquids and gases and then we come out to a definition of fluid after this video. So, what I am doing here is this is a gas cylinder and I am pushing in crystallized gas to this small bottle and the gas gets transferred to the bottle and it occupies the entire volume of this bottle. So, I am doing the same exercise here, but the containers volume has changed. But you can see that gas occupies the entire volume again irrespective of the fact that the volumes have changed, shape of the containers have changed. This is where you can compare both the volumes. Now, let us do the same thing for liquid. This is one bottle we can have the bottle of different shape now. So, what I can see here is even if the shapes are different the liquid is occupying the similar shape because the liquid occupies the shape of the container. However, as compared to gas it will not occupy the entire volume which the gases could do. Now, let us see the third experiment with solid. So, here again you can see that for the solid it occupied its own volume. It could not take the shape of the bottles different bottle shapes while for the gases it could for the liquid it could, but the solid it could not take the shape of the container right and whatever original shape the solids had that volume remained the same. The shape and the volume remained the same for the solid. So, now from there we can see that the liquids and the gases could actually flow and because of this property that they can flow they could get the shape of the container itself. And therefore, we say that the liquids could flow the gas could flow and that is why we say that they are called fluids. So, I will say liquid and gas are called fluids while the solid could not take the shape of the container because it could not flow. And because it cannot flow we say that solids cannot be configured as fluids with the liquid and gas can. And therefore, we say that solids are not fluids the liquid and gases are. So, my study of fluids will actually refer to study of liquids and gases only.