Trains run to nook and corner of the country all through the day and to keep track and maintain a database for these train schedules is a tough thing. Indian Railways does it efficiently time and again but for passengers to keep track of this is an impossible thing. So online train schedules are readily available for your perusal.
All you need to do is enter your train details or the place of starting and the destination then Viola! You have the schedule before you. According to your needs (i.e.) if you are a frequent traveller you can take a print out of the original schedule or buy a poster copy of it which is available in the internet. These schedule posters can also be availed from the railway station shops or counters for a minimal price. Train schedules for each zone are charted carefully and are updated from time to time to avoid confusion.
The Indian Railways time table is liable to change every few months and you have to keep updating yourself either through the railways site or through the IRCTC site. Not doing this might land you in a wrong perception and planning of your travel. Whenever you look for schedules see the date up to which it is valid and thoroughly check its credentials. For current details always look in to the Railways site which will provide you will the up to date info regarding the train timings.
The timings mentioned in the time tables are only approximate and never accurate as there will be many practical hurdles that the train may have to face along the journey like waiting in a signal for another train to pass. So there may be a delay in the foretold time and the passengers are requested to wait patiently, most times this delay is only a matter of few minutes. In very rare cases only the delay may extend for hours together due to some major problem in the engine or due to problems in the path of journey.
Almost every train tries to keep up with the mentioned time and most of them succeed in it too but there are always exceptions. Train schedules need to be planned effectively to avoid lags and collisions and Indian Railways maintains an efficacious time table so that trains reach the stations on time and pleases the passengers from time to time.