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docs/books/api_design_patterns/part1/chapter2.md

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+# Introduction to API Design Patterns
+
+## What are API Design Patterns?
+
+A **software design *pattern*** is a particular design that can be applied over and over to lots of similar software problems, with only minor adjustments. It is not a pre-built library but more of a *blueprint* for solving similarly structured problems.
+
+- Most often, design patterns focus on specific components rather than entire systems.
+    - e.g. If you want to add a logging system, you can use the **singleton design pattern**.
+    - This pattern is not complete
+    - However, it's well-defined and well-tested pattern to follow when you need to solve this small compartmentalised problem of always having a single instance of a class.
+
+## Why are API Design Patterns Important?
+
+- While having programmatic access to a system is very valuable, it's also much more fragile and brittle.
+    - Changes to the interface can easily cause failures for those using the interface.
+- We refer to this aspect as *flexibility*
+    - Interfaces where users can easily accommodate changes are *flexible*
+        - GUIs are flexible - moving a button
+    - Interfaces where even small changes cause complete failures are *rigid*.
+        - Backend APIs: changing a query parameter breaks old client code.
+- Rigid interfaces make it much more difficult to iterate toward a great design.
+    - We are often stuck with all design decisions, both good and bad.
+
+Page 20: 2.3.3 Overview