internet.svg image contains modified versions of computer and networking icons from Wikimedia Commons:
directory-structure.svg image contains modified versions of file icons from Wikimedia Commons:
These images are used from the Wikimedia Commons:
vancouver-docks.jpg(and thus parts of
jpeg.svg) from Dock_Vancouver.JPG
The Interactive Colour Mixer idea and basis of the code there is from the jQueryUI example color picker (which is CC0 licensed).
The CSS template in Responsive Design and Code Snippets combines ideas from the HTML Boilerplate main CSS for
html, and the style of (ahem) bettermotherfuckingwebsite.com.
The download times in Using Images on Web Pages were arrived at by taking download times from speedtest.net (in early 2015), and finding mobile providers in the 10Mb/s (megabits per second) range. Taking the example 10 megabyte page, we get 10MB × 8bits/byte ÷ 10Mb/s = 8 seconds. Home Internet providers' speeds seem all over the place: I guessed 20–40 Mb/s just to have numbers to work with.
The 2MB per eight-megapixel image values based were on the pictures I happened to have on my phone.