What does below pictogram mean?

The person who makes it has no need for it. He who purchases it does not use it. The person who does use it does not know they are. What is it?

Why is it very easy to weigh a fish?

Can you place six X (crosses) in below board without making three in a row in any way ?

I come in different shapes and sizes.
Parts of me are curved, other parts are straight.
You can put me anywhere you like,
but there is only one right place for me.
What am I?

Your last good ping-pong ball fell into a narrow metal pipe embedded one foot deep in concrete.
How can you get it out undamaged, if all the tools you have are your tennis paddle, shoe laces, and plastic water bottle, which does not fit into the pipe?

A man was driving a black truck. His lights were not on. The moon was not out. A lady was crossing the street. How did the man see her?

What is the next number in this matchsticks series riddle?

An equation has been laid down using a few matchsticks. However, as you can see, the equation is not correct. Can you correct the equation if you are allowed to add or remove 5 matchsticks?

How can you leave a room with two legs and return with six legs?