The single market has been described as "Europe's biggest achievement", during a special debate in Strasbourg to mark its 20th anniversary.
It was formed at the end of 1992, following the removal of barriers to the free movement of goods and people.
Speaking during the anniversary debate on 25 October 2012, German liberal MEP Jürgen Creutzmann said it allowed people across the EU to work and study wherever they wanted, boosting trade and productivity.
Single Market Commissioner Michel Barnier agreed, but said the EU needed to be "bold and ambitious" in taking the single market forward, despite the current crisis.
He has recently put forward proposals for a "Single Market Act II" to remove remaining barriers such as liberalising the energy industry, reducing costs of online payments, and allowing more competition on Europe's railways.
It was a result of the 1986 Single Market Act, which was seen as a way of boosting the economy of the EEC, as the European Union was then known.
The single market relies upon removing tariff and customs barriers within the EU, as well as the mutual recognition of standards, meaning that member states are legally obliged to recognise goods produced in another EU country.
The European Commission
that 2.75 million extra jobs have been created as a result of the single market.
However, Dutch socialist MEP Cornelis de Jong said it had led to competition in working conditions, and urged the Commission to consider the idea of a European Minimum Wage.
A report on the future of the single market was voted on during the daily
later in the day.
to how the plenary sessions work.
on the use of simultaneous interpretations, on the European Parliament's website.