There are just a few criteria:

1. The external website must have a decent amount of searchable data; nobody likes to visit a site that constantly returns no results found. Even ajvocab.com fails this criteria, but we get a pass.

2. The site must respect people's privacy. Unfortunately very few websites meet this condition, and often when a site claims to respect privacy it's nugatory because the site utilizes one (or more) of those nearly ubiquitous web analytic tools; so every detail of your visit is tracked, recorded, and aggregated by a third party that could give a rat's ass about privacy. Here is a perfect example of this; three trackers on “we-are-committed-to-the privacy-of-our-visitors” noaa.org—blocked by duckduckgo's privacy essentials. (And why does a government-funded agency use these intrusive technologies? Maximize profits?)

   Had we been too strict with this policy there would be few links. Therefore we decided to take a more pragmatic approach: we give preference to sites with the best privacy practices and exclude those with the worst. The displayed icons are roughly ordered from left to right in order of best to worst privacy practices. This is not automatically calculated and must be occasionally reviewed.

   If you are unfamiliar with the intrusive tracking that seems to have become the core of the internet, we suggest that you install duckduckgo's privacy essentials and/or use the brave browser; both block trackers and give an indication of how much (or little) a website values privacy.

geography links, for example.

The icons on the vocabulary page change to reflect the category. So there are special sets of icons for, i.e. places, artists, birds, and music. Not every category has a special set of icons.

We are always looking for sites that offer good content and respect people's privacy, so before suggesting a site first make sure the website meets these basic criteria.