A lot has been written about design patterns. The most prominent and always recited example is the well-known book Design Patterns by the Gang of Four (GoF). It describes common situations in software design that are solved using specific implementation patterns.
Whereas the design and motivation for specific patterns are still valid today, the actual implementation may have changed, especially in the enterprise area. Besides the well-known design patterns which are applicable for all kind of applications, there are also a lot of enterprise-related patterns that have emerged. In particular, a variety of J2EE-related enterprise patterns came up in the past. Since we are in the age of Java EE 8, not J2EE anymore, there are now easier ways to implement various patterns which tackle specific situations.