Added chapter 2

docs/books/api_design_patterns/part1/chapter1.md

@@ -78,3 +78,23 @@ What is the purpose of building an API in the first place?
 - We could think of simplicity as the number of endpoints.
     - However an API that relies on a single `ExecuteAction()` method just shifts complexity from one place to another.
 - APIs should aim to expose the functionality users want in the most straightforward way possible, making the API as simple as possible, but no simpler.
+- **Make the common case fast**
+    - Whenever you add something that might complicate the API for the benefit of an advanced user, it is best to keep this complexity hidden from a basic user.
+    - This keeps the more frequent scenarios simple and easy whilst enabling advanced features for those who want them.
+    - e.g. Image a translation API. `GET /translate?lang=en`, allowing the user to add a specific language model as a mandatory field is complex for the average user and will slow down basic scenarios.
+
+### Predictable
+
+APIs that rely on repeated patterns applied to both the API surface definition and the behaviour.
+
+Users very rarely learn an entire API, they learn the parts they need to and make assumptions when they need to make additions. e.g. if a query parameter is called text in one endpoint, it should not be called string or query in another.
+
+APIs that rely on **repeated**, **predictable** patterns are easier and faster to learn; and therefore better.
+
+### Summary
+
+- Interfaces are contracts that define how two systems should interact with one another.
+- APIs are a special type of interface
+- Web APIs are again a special type of API that is exposed over a network.
+- **Resource-oriented** APIs are a way of designing APIs to reduce complexity by relying on a standard set of actions, called *methods*, across a limited set of resources.
+- Good APIs are generally: *operational*, *expressive*, *simple* and *predictable*.