Trading - Mobile Authenticator required?

Because no one wants to wait 3 days to complete a trade.

With mobile you don't need wait the 3 days, so i really recommend use it.

Because if it's not, the items will be held up to three days by steam before being given to you and your trade partner

This was implemented for ensure that your the person who's making the trade and not somebody who stole you're account, and yeah the 3 day trade hold :)

if you don't want to add it to your phone, you can use this instead.

Thank you all for you answers! :)