I practically lived out of different hostels, and one a few peoples' couches, for about 11 months once:
Hostels, at least in (most of?) Europe, are essentially cheaper hotels, usually without a minibar and with much less upselling. Or, in terms I know from US cinema, they're like motels without the car culture aspect.
I must have stayed in something like 30 different hostels in Poland over the course of last decade; it was always in single bed or two-bed rooms, with the whole room rented for me. I never used booking.com, though, but always did a Google search for "hostele w $city", and reserved room via phone or web form.