Josh Buchea rounds up all the stuff that could be put into the <head> for various reasons.
Fun fact I just learned, the only acceptable elements in the head are <link>, <script>, <meta>, <title>, and <noscript> (update: also <base> and <template>). If you put anything else in there at all, all browsers will abruptly end the <head> and start the <body>.
Also, this proliferation of stuff-in-the-head is at least in part why manifest.json is a thing.
