While the UK was in the EU, companies could buy and sell goods across EU borders without paying taxes (known as tariffs). If there is no trade deal, businesses will have to start paying these taxes, which could make things more expensive.
As well as a deal on goods the UK would like one on services, which are a big part of its economy. This isn't part of the talks, but separate agreements on things like banking are still possible.
Agreements on areas like airline safety, medicine and the sharing of information about security threats are also important...more
