While most of us loathe the huge paper works and reading the various treaties (except for maybe lawyers), we became all aware of the Article 50 of the Lisbon Treaty, especially after post-UK referendum world.

What it says,

• In order to exit from the Union, the United Kingdom will have to trigger Article 50, which says that any member state may decide to withdraw from the Union in accordance to its own constitutional requirements.
• It also says that the triggering will basically trigger a two-year negotiation period, which can be extended with the support of all members and if not, all relations will cease to exist between the exiting state and the bloc.

The biggest fallout:

• The biggest and probably most troublesome fallout of the Article 50 is that after triggering it, the exiting state which could be Britain in this case, cannot negotiate any trade deals inside and outside of the European Union.

This means if the Article 50 negotiations fail, Britain will have no deals in place (except the ones, which is currently not negotiated as the part of the EU) after two years of triggering it.

That is why British delegates all around the world talking with global leaders and their counterparts to prepare the stage so that a deal could be agreed at the earliest after leaving the bloc.