Rohit
When programming people with lot of programming experience have found that usually there are some snippets of code which is quite often repeated most of the time so they have taken em generalized piece of code and kept it aside and that becomes "Design pattern" for that particular type of code.
You can learn more about design patterns by reading "Desing Patterns"
you can think of design patterns as pearl of wisdom from you elders so that you do not go about reinventing the wheel.
Hope it helps.
PS: you can e-mail me at
[email protected] and i can even send you a free digital book named "design patterns" by James W. cooper.