Answer:
What gets broken if it’s not kept?
It weighs next to nothing but no one can hold it for long. What is it?
Lots of them make up a word, And lots of words are in them. It's easy when you think about it. A while ago we stamped and mailed them.
Though I should be unique, you've made most of us the same. I would be stronger, if my characters were stranger.
Temporary evidence of where you've been strolling
Easy
Animal
Difficult
Food
Funny
Kids
Logic
What am I?