This might seem confusing because we typically think of fluids as liquids. However, the term "fluid" encompasses both liquids and gases. Fluids share the following properties:

* They can flow: This means they can change shape easily.

* They cannot withstand shear stress: This means they will deform continuously when subjected to a force applied tangentially to their surface.

So, while a solid has a fixed shape and can withstand shear stress, a fluid does not.