Here's why:

* Spiral structure: The Milky Way has spiral arms, which are regions of higher density of stars, gas, and dust.

* Bar: It also has a central bar structure, which is a elongated region of stars extending across the galactic center. This bar is thought to play a role in feeding material into the galactic core.

So, the Milky Way's classification is SBb, meaning it is a barred spiral galaxy with moderately wound arms.