Hostels

Meet other travelers and get a good night's sleep without breaking the bank. Hostels offer communal sleeping in a dormitory with other travelers, and usually include shared bathrooms. If you're willing to pay a bit more, you can often upgrade to a private room. You can find a range of hostels dotted all over Europe's cities and often in smaller towns too.
 

One of the top online hostel booking engines is Hostelworld.com. They offer hostels and B&Bs throughout Europe.