Once you’ve mastered the basics, you can add to your searches with extra context. The pop-up results have a search bar at the top: tap here to type out an additional query (or tap the mic icon to use your voice instead).
So you might ask “What can I put this on?” for a condiment (Google’s own example), or ask “Why is this trending?” or “Which country is this in?” It’s a useful way of creating searches that are a bit more complex than simply searching on an image.
What you can’t do yet, as far as I can tell, is select multiple items on-screen and then compare them or run multiple searches at the same time. Plus, some of the results can be hit-or-miss, depending on the quality of your selection and how many other similar-looking images are on the web.
Nevertheless, this seems like a genuinely useful addition to Android. The real beauty of it is the way it works on top of other apps: an Instagram caption, for example, or a webpage image or artwork on a podcast. Whether the app in question lets you select text or save images, it doesn’t matter.
To quit Circle to Search, tap on the X in the top-left corner. Tap on the three dots in the top-right corner, and you get options to see your Google search history (across all apps and services) and delete the last 15 minutes of your search history.