Every country in Europe has its own way of naming their roads. In Great Britain and in Ireland they use the letter M followed by a number for their motorways. Most mainland countries use the letter A followed by a number for their motorways. This of course can lead to some confusion. If you drive from Amsterdam in the Netherlands to Rome in Italy, there are a number of motorways you drive on and there are different names and numbers for them. Netherlands: A2-A12, Germany: A3-A67-A5, Switzerland: A2, Italy: A9-A50-A1.
So seeing that we are one Europe, they have decided to make it just that tiny bit easier for us. Instead of having to follow all those different names, we only have to follow one: E35! That will lead you directly to Rome!
There are others as well: Cork in Ireland to Omsk in Russia: follow the E30. Lisburn in Northern Ireland to Seville in Spain: follow the E1. Kaaresuvanto in Finland to Gela on Sicily, Italy: follow the E45.
All E-roads are crossing borders. Sometimes one, sometimes more. And not only in Europe: there are some routes even into central Asia! Some countries use the E-numbering as their primary motorway numbering, like Belgium. The United Kingdom doesn't aknowledge the E-roads at all. Ireland has only recently (2007) started incorporating them in their road-system.
For me as a professional driver, using E-roads makes life easier. As long as you know where you're going that is...
For more E-words, please check out ABC Wednesday and join in the fun!