When I go through the wash, I occasionally come back single.

knob, bell, frame, revolving, sliding, trap. The Polkadot. Knock-knock-knockin' on Heaven's...

A house for birds, I am. Or any avian, I suppose. Find me at a zoo, a menagerie, Or another place, you choose. In me, birds roost, Breed, and thrive… What am I? Here’s a boost- I start with A and end in why.

I've been around for many years, though my design has changed a lot. From gaseous tubes to leds, most people have several of me.

No legs, but loves to float, Can wear a sail, a motor but will not gloat. Dances on the waves of the ocean blue And can carry a captain and maybe a crew