Answer:
Useful term for when you need to start a fire or notice someone with the same shirt as you.
What do you call the mother-in-law of your sister's husband?
Tickle with your fingers and a song it will sing. Be careful, though, you may break a string. What is it?
What is something yet nothing, but if you fill it up it will disappear?
What goes through towns and over hills but never moves?
If it’s information you seek, come and see me. If it’s pairs of letters you need, I have consecutively three. What am I?