Update README.md

README.md

@@ -23,6 +23,24 @@ How to Use
 Generally these headers do not have dependencies and are intended to be included directly into your source (check each header for specific documentation at the top of the file). Each header has a LIBNAME_IMPLEMENTATION symbol; add this to a single translation unit in your code and include the header right after in order to define library symbols. Just include the header as normal otherwise.
 
 Examples and Tests
-------------------
+-----------------
 
 Some headers also have example code or demos. In this repo just look for the corresponding examples or tests folders. The example folders are particularly useful for figuring out how to use a particular header.
+
+FAQ
+---
+
+> *What's the point of making a single file? Why is there implementation and static functions in the headers?*
+
+Including these headers is like including a normal header. However, to define the implementation each header looks something like this:
+
+    #define LIBNAME_IMPLEMENTATION
+    #include "libname.h"
+
+This will turn the file into a header + c file combo, one time. The point of this is: A) handling the header or sending it to people is easy, no zip files or anything just copy and paste a single file; B) build scripts are a pain in the ass, and these single-file libs can be integrated into any project without modifying a single build script.
+
+> *Doesn't writing all the code in a header ruin compile times?*
+
+The stigma that header implementations slow compile time come from inline'd code and template spam. In either case every single [translation unit](https://en.wikipedia.org/wiki/Translation_unit_(programming)) must churn through the header and place inline versions of functions, or for templates generate various type-specific functions. It gets worse once the linker kicks in and needs to coalesce translation units together, deleting duplicated symbols. Often linkers are single-threaded tasks and can really bottleneck build times.
+
+A well constructed single-file header will not use any templates and make use of inline sparingly. Additionally well constructed single-file headers use a #define to place implementation (the function definitions and symbols) into a **single** translation unit. In this way a well crafted single-file header is pretty much the best thing a C compiler can come across, as far as build times go. Especially when the header can optionally #define out unneeded features.