I can be kept, I can be broken, I am mightier than any sword, and yet, add one letter to me, and a sword is exactly what you’ll find. Now, then, what am I?

If you don't want uninvited guests moving in with their entire stock and barrel, you need me to keep them out.

I can lock your door or dash down the street. One holds things shut, the other moves feet.

A metal body and U shaped neck Guards without a code Give a pull to check It's in secure mode

Around they spin, in painted horses' stride, a music box that plays outdoors, where dreams take a ride. A fairground's round dance, where laughter and joy abide.