What is "backpacking", someone told me you can travel Europe that way?

Backpacking is simply to travel around with all of your stuff in a backpack. Usually getting from place to place by walking or hitchhiking.

Travel with a backpack, usually hitchhiking, duh...

backpacking is traveling with your only belongings you have in your backpack, except the clothes that you already have on.

it is hiking around living out of your back pack. meaning you walk across europe staying youth hostels during the nights and carry everything that you need in your backpack.

If you do this be sure to plan your trip carefully and give yourself plenty of time to get from place to place.

yeah just camping out and traveling with a everything on you. i go backpacking in the wilds hike a long ways in then set up camp hang out for a day or 2 the hike back out. Its very relaxing and you never feel more free.

its just basically traveling with the bare necessities and using the least amount of money possible while there.

For hardcore travelers who want to experience the "real" local way of life, not tourist traps and no luxuries (it means no 5-star hotels)

Its very cult-ish.

Unlike what most of the other answerers say, most people 'backpacking Europe' use the train, or at least the long distance buses.

Many people buy a train pass, take a pack or small suitcase and stay in hostels or small hotels.
Without much of a plan, without reservations and with a lot of freedom.

Best to do if you travel alone or with a friend.
When you get a group bigger than four you need to make reservations, specially if you travel in summer.

"backpacking" is a certain style of travel. It usually means low-cost international travel with minimal luggage and frugal accommodations. Typical is that you organise everything yourself.

See http://en.wikipedia.org/wiki/Backpacking_%28travel%29

In Europe backpacker's either stay in hostels or bring their own tent and stay on camping sites. Backpackers tend to buy food in supermarkets and cook their own food where possible instead of eating out.

http://en.wikipedia.org/wiki/Hostel

Read this for all the info you need about Backpacking in Europe
http://europe4vacations.com/europe-and-european/backpacking/backpacking-europe.html
Hope this helps