Code examples can be copied to the clipboard by selecting the ⧉ icon in the upper-right hand corner of most code blocks. (Sometimes the code copied will include some of the subsequent code blocks, following the source material's behavior.)
Most code samples will not work if you select text and copy-paste: it will be missing tab characters that are significant to Inform. Use the copy button.
Writing with Inform, The Inform Recipe Book, and the documentation examples are a part of the distribution of Inform 7 by Graham Nelson. For descriptions of them, see Writing with Inform's Preface, The Recipe Book's Preface, and About the Examples. For more detailed credits, see Writing with Inform's Acknowledgements and the Recipe Book's Acknowledgements.
Thanks go to Juhana Leinonen for Borogove. The playable examples use Andrew Plotkin's GlkOte and Quixe, distributed under an MIT License. The Quixe pages are offered in case one's off-line with a local copy of this edition; there isn't otherwise any reason to prefer them to the Borogove links. (Borogove itself uses Quixe).
A few examples lack Borogove/Quixe links because they're Z-machine only or their purpose is to write an EPS file to the project's materials dir and there's no suitable way to demonstrate them.
Sections 1.3-1.7 of Writing with Inform as presented here omit some details particular to individual platforms. You should check them within the Inform app itself to see the appropriate platform-specific content.
This edition was reformatted by Zed Lopez; it has been modestly adapted to suit the format changes, with my apologies for any errors I may have introduced.