What is this metal strip?

Is this attached to the botomof door, as in it moves when the door does?

It is a door threshold and sweep - it is to close the gap between the door and the floor. Helps with weatherproofing and keeping critters out.

Hi Melinda, I think Sassy is correct. It's for weatherproofing.

Yes it is a door sweep as Sassy says. Mainly to keep the weather out. They are mounted on the side of the door in the direction the door opens. If the door opens to the inside it's mounted on the inside. If the door opens to the outside it's mounted on the outside. I assume your door opens to the inside of the garage so it's mounted on the inside.

It appears to be a threshold that protects the floor from getting damaged going in & out of the door. It is used for both tile & carpet and should be on the inside of the door (in the home).

If it was on the outside of the door you would not be able to close the door. If your door opens outward, then it would be on the outside of the door.

So you could take it off and just buy some insulating tape on the underside of the door? unless it rains inyour kitchen or garage, I see no point. If water comes into the garage, then the kitchen, get a rubber sweep on the outside of the door

Was the garage attached to the house after the doorway was built? The builders possibly thought that the door was (at that time) going to open from the outside.

Also, is your garage unheated in the winter? Depending on what part of the country you live in, sometimes due to the cold air in the garage, it is considered an 'outside' area.

With an attached garage, the interior garage door is a part of your firewall (requires a solid core/fire rated door, self-closer, and has to seal) so it could be part of the seal that builder used. If so, it should seal against the threshold.

It does none of those precautions, nor is there a self closer, solid core door, etc. Why I’m baffled.