What is the correct use of auto?

[Hans W. Uhlig]

I have been reading through the specification and playing with D more 
and more, what is the purpose of auto. I can understand in languages 
with scalar types handling datatypes on assignment but on a strictly 
typed language like C or D when would auto(as a variable declaration) 
provide more useful functionality then it removes from readability.

When would this be useful rather then simply specifying the type?