The person who makes me doesn't need me. The person who buys me doesn't use me. The person who uses me never knows it. What am I?

I have four legs in the morning, two at noon, and am strongest with three in the evening. What am I?

The more you take away from me, the bigger I become. What am I?

I weigh nothing, but you can see me. Put me in a bucket and I make it lighter. What am I?

I disappear the moment you say my name. What am I?