How is the transition phase regulated?
In the transition phase stretching till 2020, which can be extended to 2022, the UK will remain in the EU-market and in the European Customs Union.
The UK will no longer have a say in Brussels and will not remain a member of any EU institutions.
All EU regulations will continue to apply and new EU regulations must be accepted in the transition period.
This will act as a grace period for businesses, and also as a negotiation period to clarify what needs to be done for a lasting relationship between the two sides.
London may, however, conclude international trade agreements during this period if these only enter into force after the transitional phase.
Deadlines for approval
If the withdrawal agreement is not approved by British Parliament by March 29, 2019, there will be no transitional period.
In this case, the UK will crash out of the EU. This abrupt break will create great uncertainty for citizens, the private sector and is likely to trigger an economic crisis.
In addition to the approval of parliament in London, the approval of the European Parliament (EP) is also necessary –already announced by the EP president.
Rights of UK and EU citizens
More than three million non-British EU citizens reside in the UK and around one million Britons live on the continental EU.
They will be able to stay in their present residing countries and continue to work, study or follow other activities. EU citizens who arrive to live in the UK till the end of the transition period will enjoy the same rights.
However, once Brexit comes into effect, EU and UK citizens will need a visa to stay longer than 90 days in each sovereign political federation.
A hard Irish border?
The border between the EU state of Ireland and Northern Ireland has been the thorniest issue in negotiating Brexit.
The withdrawal agreement on this issue hopes that future talks can find a long-term solution for how trade will work between the EU state and Northern Ireland.
If nothing is agreed upon by the end of the transition period, the dreaded backstop option will kick in.
In this, Northern Ireland will have a different customs relationship with the EU, and will have to follow rules and regulations of the single market. This also means the UK will remain in a single customs territory with the EU.
The future of Gibraltar
The UK and Spain agreed to terms related to the British overseas territory of Gibraltar prior to Sunday's divorce agreement. Spain claims the British territory for its own but is not guaranteed this right.
Spain's Prime Minister Pedro Sanchez said the agreement "will allow Spain to negotiate directly with the UK over Gibraltar" in future.
The EU and UK agreed that commuters between Gibraltar and Spain can continue to work in Gibraltar without any problems. The withdrawal agreement also regulates tax issues and clarifies fishing rights.
"With Brexit, we all lose, but on Gibraltar, Spain wins," Sanchez said.
The divorce bill
Though the UK has argued it does not owe the EU anything when it Brexits, the withdrawal agreement has terms for "a fair calculation method" but not an actual number.
However, the figure of about $50 billion or 39 billion pounds was agreed upon by Britain in 2017 and will be paid over a number of years.
This means the UK will continue to contribute to the EU budget in the transition period as well as other possible outstanding costs.
The British government guaranteed to stand up for financial obligations during its time as EU member.
Without the treaty, EU taxpayers would have to step in.
In case of disputes
The UK will remain under the European Court of Justice (ECJ) during the transitional period.
If there are any issues on how either side interprets the withdrawal agreement, a joint committee or arbitration panel will be expected to come up with solutions.
If the UK remains in the single customs union after the transition, according to the BBC, the ECJ will not have authority to adjudicate.
After the transition
The withdrawal agreement is intended to create legal certainty until the end of the transitional phase – only then will Brexit really take effect.
A comprehensive trade and partnership agreement will clarify what happens next.
To date, there is a 26-page political declaration of intent, which was also approved at the EU special summit and a 586-page agreement, which has to pass parliaments of the UK and EU, as mentioned before.
The central point is the vision of a "free trade area that includes deep cooperation on rules and customs."
As yet there are no tariffs or quotas. If the withdrawal agreement fails, the basis for the future for bilateral relations is lacking.