For me, the biggest surprise with Chrome Incognito mode was discovering that separate Incognito windows share cookies with each other.<p>I had been logging into accounts in an Incognito window, then opening a new Incognito window to visit other sites assuming they were new private sessions. One day I was surprised to find myself already logged in to someplace I visited, in a new Incognito window.<p>At that point, I discovered that much of my Incognito activity across the web for the previous few months was in fact tracked to my identifiable, logged in accounts. And that my multiple accounts (for work, other work, personal) were potentially being linked together, which I did not want.<p>For months I hadn't noticed because I tended not to open the same sites more than once. So I hadn't realised that cookie sharing was happening, which means cross-site tracking was happening.<p>Now I don't use Incognito windows any more. There's no point, they aren't what I expected.<p>Now I use Firefox Containers to segregate account logins and reduce unwanted profiling (e.g. with YouTube), and Temporary Containers when I want a new, ephemeral session.<p>Firefox Temporary Containers actually do what I'd mistakenly thought Incognito mode was for.