Blend shapes provide the appearance that one shape transforms into another in a natural way. For example, you could use one to animate a character’s mouth changing from a neutral form to a smile. This is accomplished by creating a replica of the object, which is then manually altered to a different shape.
How to use Blend Shapes in maya: To utilise automated settings, open the Shape Editor and click the Create Blend Shape button. In the Shape Editor, go to Create > Blend Shape Deformer. To begin, click the Options icon to specify options. To use automated settings, right-click in an empty area of the Shape Editor and select Add Blend Shape Deformer.
We made different facial expressions using a model of a head, then we selected them all and used blend shape in deform
And we used it to make an animation with them