A "dialogue" about Ireland and Northern Ireland has been launched separately
The Brexit timetable and negotiation plan has been announced by the lead negotiators.
Brexit Secretary David Davis and EU chief negotiator Michel Barnier said discussions would be split into three stages: citizen rights, the single financial settlement and other separation issues.
A "dialogue" about Ireland and Northern Ireland has been launched separately.
Mr Davis appeared to have conceded to EU demands by agreeing to a "two-phased" Brexit negotiation: first settling the divorce terms before discussing future trade relations.
He had previously said not settling both elements simultaneously would be "the row of the summer".
Mr Barnier spoke at a press conference after the first day's talks to confirm that settling priority issues would build "trust on which to negotiate a new relationship".
He also reassured: "We will never work against the UK."
Both men will meet for a week every month to negotiate, and use the time in between to "work on proposals".
They also included symbolic quotes in their separate statements. Mr Barnier quoted one of the EU's founding fathers,
Jean Monnet, saying in French: "Ce qui est important, ce n'est, ni d'être optimiste, ni pessimiste, mais d'être détermine."
It translates as: "What is important is not to be optimistic, nor pessimistic, but to be determined."
Mr Davis chose a quote from Winston Churchill instead: "The pessimist sees difficulty in every opportunity. The optimist sees the opportunity in every difficulty."
He added after: "Bridging between Churchill and Monet, I am certainly a determined optimist."