Youth Hostels History
The first youth hostel was founded by Richard Schirrmann around 1909. Schirrmann was a German teacher who organized trips and visits with his students. During one of these excursions, a sudden rainstorm forced his group to seek shelter in an empty school.
It was then that Schirrmann had the idea of using schools that were empty during holidays as guest houses for young people that were travelling in groups in the countryside. The idea caught on very quickly, and by the 1930s there were more than two thousand hostels in Germany.
The idea spread out in the rest of Europe, and after an important international conference in 1932, the idea was exported to the United States and many other countries, and the International Youth Hostel Federation was born, with the idea of providing cheap accommodation for young travellers.
With time, the concept of hostel has broadened, and now hostels accept guests of all ages, providing cheap but comfortable accommodation and a unique atmosphere that cannot be found in hotels.

Hostels Equipment
If you are travelling for a long time, buy yourself a good backpack, which fits you comfortably, and do not exceed in loading it - a heavy backpack can be very painful to carry when it's summer and it's hot. Choose comfortable shoes, and keep cool shoes for evenings out.
Hostels most often provide you with sheets (often at an extra cost), but you should bring your own, just in case. Some hostels might not allow sleeping bags, for reasons of hygiene (you might have been sleeping anywhere with a sleeping bag, and hostelling is not the same thing as camping).
Some hostels will provide you with a so-called sleep-sheet, which is two sheets sewn together, so they form a sort of sack. This way the bed stays clean. It is not as common as it used to be years ago.
You should also bring your own soap and towels, since only some hostels provide these, usually with an extra charge.

Hostels Social Life
Hostels are definitely the place for socializing. Since the guests in a hostel are mostly younger people, there are plenty of occasions to get to know other travellers. Some hostels organize parties, meetings or competitions, or have a bar within or just outside their premises where people can meet and chat to fellow guests.
Hostellers are generally more interested in meeting other people than your average tourist, so it's much easier to get in touch with them, share common interests and exchange advice, tips, etc. Many people travel on their own all over a country or continent more than a year long, and rely on chance meetings to make friends.
Remember: you can always meet people who have opinions (on politics, sex, religion, your country) that are very different from your own, so you must be prepared to be tolerant and understanding other people's positions and views on life. Without a doubt, this will certainly enrich you and broaden your perspective. So if you go to a hostel, expect to meet new friends, (especially if you speak some languages) and put on your best smiling face. Who knows, you might make the best friendships of your life!

Youth Hostels vs Hotels
There are several types of hostels nowadays, and all of them tend to have their special characteristics; some are more like standard hotels, some are a completely different experience. The main difference is that most hostels offer accommodation in dormitories, or shared rooms. Dorms can be bigger or smaller, can be for males/females only or mixed, but anyway this means that you can share your room with strangers.
Although many hostels now provide private rooms with en-suite facilities, the atmosphere is still very different from that of your average hotel. Whereas hotels only tend to just provide their customers a comfortable place where to spend the night, hostels tend to have more of a social atmosphere which often is derived from sharing dining tables, washing machines, dryers, and much more with with other guests.
Many hostels organize parties and excursions for their guests, and many have a bar where people can meet and get to know each other. In a hostel it is much more likely to start a conversation with a fellow traveller or to be asked for advice, tips and information by someone you have never met before.
Basically, hostels are generally a good place to make friends, to meet people from far away countries with ways different than your own, to exchange tips on clubs, museums, shows, shopping and the like.

Different kinds of hostels
Hostels come in all shapes and sizes nowadays.
City hostels tend to lean more towards the social/fun aspect of city life, offering information about pubs, tours of the city, thrift shops and night clubs. They can be much noisier than country hostels, since they often have no curfew and are open 24 hours a day. The bigger the hostel, and the more night-life oriented the city it's in, the more social life you will find.
Country hostels are a very different thing. They're mostly frequented by people who are travelling through the country, possibly walking or hiking. This means people wake up earlier, and go to sleep earlier, and usually like it quiet!

How long can I stay in a hostel?
Some hostels won't allow you to stay longer than a couple of weeks, since the idea of hostelling is that people are travelling across a country, and not staying in the same place all the time. But many others will not mind if you stay longer: after all, you are indeed a customer! Some hostels will require you to prove that you are an international traveller, since it wouldn't make sense for a hostel to be full of locals, but this is not too common.

Group bookings
Not every hostel is ideal for group bookings, since some can be small. The best idea is to book well in advance, so you can be sure to find room for everyone in your group.
What kind of facilities are available in hostels?
Most (but not all) hostels will offer a laundry room, telephone, Internet connection, lockers for your precious stuff, and a breakfast service. Some will offer more. Every hostel/hotel in our list has an indication of the facilities it has, so you can be sure to get what you need. If you're travelling with a dog, remember to check whether the accommodation you choose allows them in!

Do I need to book hostels in advance?
Definitely yes, and that's why we're here. Especially during peak seasons, and even more in the most famous cities and resorts, hostels can be fully booked and have no room for you, especially if you're travelling with many people. Booking in advance is a good idea, since you get rid of worries and do not need to walk across a city with a heavy backpack looking for accommodation. It might detract a bit from the sense of adventure, but you'll definitely have much more time to have fun!

Is breakfast included in hostels? Can I cook in hostels?
Usually, breakfast is not included in the price, but it's reasonably cheap and abundant in quantity. Some hostels offer cooking facilities, such as a kitchen complete with pots and everything you need. Other hostels will be more than happy to give you advice about the cheapest bars and food outlets in the neighbourhood.

Age limits
Some hostels do have age limits, and might give precedence to younger travellers (especially Youth Hostels in Europe), or exclude them (if they have a bar in the premises), but most hostels will welcome guests of all ages, and will even accommodate small children and provide smaller beds and cribs if asked in advance.

Curfew
Some hostels will have a curfew, some won't. It largely depends on the type of hostel, on the owners' policy and on the location of the hostel (there's not much use in being able to come to the hostel at three in the night if the hostel is in the mountains!). Many hostels in our directory have information on their curfew policy right in their description.

Lockout
Some hostels might have a lockout period. This is usually around lunchtime or in the early afternoon, and is meant to let the hostel's staff clean the premises, or if the place is owned by a person, to allow her/him to go out and make supplies, etc. It is not so common any more, so check with the hostel's staff if you want to be sure.

Dormitory vs Private Rooms in hostels
A dormitory is a room with several beds (often of the bunk type), all of which can be booked individually by different guests of a hostel.
It is also called a shared room, since you share the room with other guests. Dorms can vary from 4 to 20 or more beds, and some hostels have separate dorms for males and females, while others do not make a difference and offer mixed dorms.
Dormitories are always cheaper than private rooms in the same structure, and generally require people to be a bit more adaptable, since your room-mates may go to sleep or wake up earlier or later than you do, have different habits than you, or snore...
But dorms are often great fun, since it's much easier to get to know fellow travellers if you share the room with them! After all, the loss in privacy is counterbalanced by many social advantages.
While dorms were the default option of most hostels years ago, most hostels now also offer private rooms, which usually have 2 to 4 beds, sometimes even with en-suite WC and shower. In this case, staying in a hostel is very similar to staying in a normal hotel, apart from all of the social chances you will have during communal moments (breakfast, evening, etc.).

Europelowcost, worldwide youth hostels price comparison
http://en.europelowcost.com/hostels.aspx