It all started with a book called Design Patterns - Elements of Reusable Object-Oriented Software. Erich Gamma et al. wrote it in 1995. Ever since then it has had a strong impact on object-oriented design and programming.
The idea is to avoid inventing a new wheel every time you need one. Instead, having found a good solution to a recurring problem, you can reuse that solution. You may have to refine it a bit, but then you'd wind up with a new and perhaps better version of it.
Software is not the only craft that can be helped by design patterns. In his foreword to the book, Grady Booch has this to say:
"The importance of patterns in crafting complex systems has been long recognized in other disciplines. Christoffer Alexander and his colleagues may be the first to use a pattern language to architect buildings and cities. His ideas, and the contributions of others, have now taken root in the object-oriented software community. In short, the concept of the design pattern in software provides a key to helping developers leverage the expertise of other skilled architects."
A sizable part of the Certified Software Architect Microsoft Platform program is about patterns. There is a difference, though. The Gamma book is about rather detailed and technical object-oriented patterns. In contrast, the program's patterns are high-level and business-driven architectural patterns. This is because the Gamma patterns are object-oriented, while the program patterns are service-oriented.
To give you an idea of what they are, here's a far from complete list of patterns you'll meet in the program.
These are just a few of the patterns you'll find in the program. They can be a good help to your team, getting projects to fly, fast and safely.
Being as business-driven as they are, they align well to the corresponding business structure. This can give your product extra milage. Strong alignment to the business facilities adapting it to a changing business. This, in turn, is bound to make it more sustainable than a not so well aligned solution could ever be.