The details:

• The U.K. will remain a part of the E.U.'s single market and customs union throughout the transition but lose any decision-making capability for the bodies. It can also sign trade deals to go into effect in 2021.
• The agreement contains a "backstop" that would put a hard border in the Irish Sea and leave Northern Ireland under E.U. regulatory control if no other solution can be reached.
• The status of E.U. citizens who move to the U.K. during the transition won't change, despite Prime Minister Theresa May's wish to limit those rights after Brexit.