India has a beehive of railway networks and it is mostly a beautiful experience to board a train in India. It might look chaotic but when you have a reserved ticket in hand, there is nothing to worry about. There are many trains that travel on time and are merely canceled (the unlikely situation takes place during extreme weather conditions like fog or rain). An overnight train will save you a day of traveling and hotel bills. There are three types of trains, Inter-city (called express or mail), Superfast (connects major cities of the country within an 8-hour travel time) and Passenger trains (which stops at every station and is ideal if you are planning to de-board in a lesser important railway station). Let us not forget the dedicated tourist trains that are usually functional in hilly areas and they are called Toy Trains. These trains are smaller and slower.
There are about seven classes in Indian Railways. Different types of train offer different classes for passengers. Some of the common classification is Second Class Unreserved (Usually packed and anyone can hop aboard even without reservation), Second Class Sleeper (non a/c, requires reservation and are ideal for overnight journeys. Provision for bunks is given for person per seat reservation. This class has basic facilities and vendors come over frequently.), First Class (non a/c with comfortable sitting). Then there are a/c compartments with three categories- First Class a/c, Second Class a/c and Third Class a/c, where the facilities are brushed up according to the fares. Some trains also have ladies' compartment to ensure solo women traveler in India are safe.
Railways in India are solely handled by Indian Government. You can reserve Indian train tickets online, through agent or by going to the station. The sooner you book, the better. Otherwise you might get your name in the Waiting List of the reservation.