Riddles

The person who makes it ,sells it .The person who buys it,never uses it.The person who uses it,never knows they are using it .What is it ?

I'm light as a feather, yet the strongest person can't hold me for much longer than a minute. What am I?

The more you take, the more you leave behind. What am I?

I have cities, but no houses. I have mountains, but no trees. I have water, but no fish. What am I?

I am born every morning, but die every night. What am I?

Two boys were born to the same mother, at the same time, same day, same month and year, however they are not twin brothers. How can this be?

What has many keys but can't open any doors?

What do you throw out when you want to use it but take in when you don't want to use it?

I have keys, but no locks and space, and no rooms. You can enter, but you can't go outside. What am I?

What 5-letter word typed in all capital letters can be read the same upside down?