I just thought of another one - so there are at least 16 :-) But seriously, there is no fixed number of patterns. If you can think of another one, describe it, and give it a name, then there's one more. Of course, people will not necessarily know about it unless it's widely publicized. Best known are the ones described in the book "Design Patterns: Elements of Reusable Object-Oriented Software" by Gamma et al.
Actually when talking about patterns there are so many patterns other than design patterns like analysis patterns [Fowler], implementation patterns [Beck], architectural patterns, domain patterns [DDD], security patterns, enterprise integration patterns [Hohpe, Woolf].
Regarding design patterns, there are also domain specific design patterns like Core J2EE Patterns, SOA Design Patterns. However if mention only "design patterns" it probably means GoF's design patterns as the Design Patterns is the first book that documents software design patterns.
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