design patterns
The design patterns provide low-level solutions to solve common object-oriented problems.
Design patterns became popular after the publication of "The Gang of Four" in 1994. Although the book has been published with examples of C ++ and Smalltalk code, patterns will be useful in any language that supports OOP.
Without even knowing, an experienced developer somehow already uses them on an intuitive level. But how long time they came to this is a question. On other side, some newbies, try to use patterns for the sake of patterns. This suggests, that they know about patterns but don't understand them well.