Someone please explane me what is design pattern?

Answer 1

Design patterns can speed up the development process by providing tested, proven development paradigms. Effective software design requires considering issues that may not become visible until later in the implementation. Reusing design patterns helps to prevent subtle issues that can cause major problems and improves code readability for coders and architects familiar with the patterns.

It's not really hard to actually understand them. Take a look at this article by sourcemaking.com :
https://sourcemaking.com/design_patterns

Answer 2

Thank U ...