what is the difference between congratulation and congratulations.

Generally "congratulations" is the widely used term, and when used in singular form you use "congratulate". But sometimes "congratulate" is replaced by "congratulation" to imply act and expression both at the same time. For example below are the two sentences giving example of usage of each : "Forgetting his spite on losing he gave his congratulation to the winner." "Congratulations on your new job." In first sentence "congratulation" is specifically used to define an act of wishing some one with good or happy feelings. Whereas in second the "congratulations" are expression mainly not an act as such so used in plural form. Whenever "congratulation" word is used to define an act or used as verb if will eliminate "s" at end otherwise it will always have "s" at end.