Euroscepticism refers to opposition to further European integration, coupled sometimes with a desire to roll back integration already accomplished. Precisely what eurosceptics oppose varies from country to country: in countries not in the European Union (e.g. Norway, Switzerland, the candidate countries), euroscepticism manifests itself as opposition to joining it; in those which are members, but do not participate in the Euro (the United Kingdom, Denmark and Sweden) it manifests itself as opposition to Euro membership.
Many Eurosceptics oppose the idea of a federal Europe. They therefore oppose measures they see as leading towards that goal, such as the European Rapid Reaction Force, the constitutionalisation of the treaties, the establishment of a European Public Prosecutor (or even the establishment of EUROJUST), the extension of EUROPOL to include enforcement powers, the harmonization of taxation or social security, and the extension of codecision or qualified majority voting. They often propose radical modifications to the constitutional structure of the EU to reassert the power of national parliaments, such as establishing a chamber of national parliamentarians with power to overturn any Community act, including even decisions of the European Court of Justice.
Eurosceptics have been resposible (at least in part) for:
- the Norwegian rejection of EU membership, on both occasions
- the Swiss rejection of membership in the EEA
- the initial Danish rejection of the Maastricht treaty
- the Danish rejection of the euro
- the Irish rejection of the Nice treaty
Most UK newspapers are widely Eurposceptic and have been known to publish many anti-European stories that the European Union and their Europhile supporters feel are inaccurate or have been invented. In response they have created web sites to refute and/or explain the actual details. 
Eurosceptics now largely control the Tories in the UK; many commentators believe this is part of the reason why they lost the 2001 UK general election so sorely. For although most British voters are opposed to the Euro, they are not obsessed about it as many Tory eurosceptics are and a Mori opinion poll showed that the majority feel that the UK adoption of the Euro is inevitable.
Since the election even more extreme eurosceptics have appeared to have taken control of the Conservative party with election of Iain Duncan Smith as party leader. Some think this may be the beginning of the end for the Tories, with the new leadership threatening to lead to Europhile Tories leaving the party, and the growing Tory obsession with the EU leading to them losing touch with the British electorate.
Iain Duncan Smith sought in late 2001 to have the Tory MEPs leave the moderately pro-EU EPP for the eurosceptic UEN. Tory MEPs refused to make the move, on the grounds that the UEN was too anti-EU and contained fascist parties.