A Landau is a lightweight open carriage on elliptical springs. It is a common version of a classical coach used by fiacre-drivers (cabmen). It's main characteristic feature is a two part roof that folds forwards and backwards.
If the front part of Laundau carriage is made with glass windows, instead of cloth or leather, we refer to it as a Glass-Landau.
There is also a small two-seat version of Landauer which is called Landaulet. Analogically it is similar to a Coupé being a two-seater version of a Berlina.