Gross domestic product (GDP) is a measure for the economic activity. It is defined as the value of all goods and services produced less the value of any goods or services used in their creation.
In this visualization, the GDP per capita in Purchasing Power Standards (PPS) is used. This index is expressed in relation to the European Union (EU-27) average set to equal 100. If the index of a country is higher than 100, this country's level of GDP per head is higher than the EU average and vice versa.
Note The index, calculated from PPS figures and expressed with respect to EU27 = 100, is intended for cross-country comparisons rather than for temporal comparisons.
As a whole, Europe owes €10,125,117,000,000 - or €10.1 trillion. But it's more meaningful to look at the number as a percent of GDP. So, we want to see how much that debt is as a proportion of the whole economy - kind of equivalent to measuring your mortgage compared to the whole economic value of your household.
There's nothing inherently bad about having a huge debt - it depends who you owe it to and whether you can manage the payments. Bigger countries are also in a better position: essentially, if you owe the bank £50,000, you've got a problem; if you owe the bank £50,000,000, the bank's got a problem.
Note Debt information before 1999 is not available for EU and Euro area. The debt from 1999 is used instead.
If the gross debt is equivalent to your mortgage, the deficit is the overdraft, the running gap between your outgoings and ingoings. Big deficits mean more borrowing, and then running it up all over again to cover the costs of that borrowing.
Again, the best way to look at these is as a percentage of GDP, and Eurstat shows which countries are worst affected, this time from the end of 2010, which is the latest available data. It shows Ireland had the worst deficit then at 31.1% followed by Greece at 10.6% and the UK at 10.3%. Compare that to Germany at 4.3% and you can see the relative strengths of the economies.