What do you think was our most important invention?

What part of the world did it come from?	What period of time was it invented in?
Was it a man or a woman who invented it?	Does it get used by everybody in the world?
What other things had to be invented first?	What would the world be like if it hadn't been invented?
What other things did it allow to get invented afterwards?	Why is it the most important invention?