You can emit hair from polygon meshes and NURBS surfaces and subsurface objects.
For polygon meshes, the resolution of the object determines how many guide hairs are created — one per vertex. This has an impact on the final look so make sure that the resolution is what you want.
In the images above, one guide (styling) hair is created at each polygon vertex. As a result, there are more guide hairs around the dog's face and paws where there are more polygons.
You can emit hair from any NURBS surface or subsurface object. As with polygon mesh objects, one guide hair is created per vertex. Fewer guide hairs mean easier styling and better dynamics performance.
You can create, edit and render as many instances of hair as you like in a scene. When you create hair, a hair primitive object and its hair generator are created for each object to which you have applied hair.
Select the object from which you want to emit hair.
If you branch-select an object, hair is applied only to the parent object, not to the whole branch of objects.
Choose Create 
Hair from Selection from the Hair toolbar.
Guide hairs appear on the emitter object, sticking out in the direction of the object's normals. One guide hair is created at each vertex.
Guide hairs are curves that you use to style the hair — styling operations are described in Styling and Animating Guide Hairs.
The Hair property editor also opens as soon as you create hair. This lets you view the render hairs and set their properties — see Viewing the Hairs for more information.
