What is t$$anonymous$$s

Hi. I often read and try to answer questions on Unity Answers. ---------- During the past few days, I've noticed that many questions include this thing: t$$anonymous$$s. I searched on the web but still didn't understand anything. Also, there isn't any official documentation about this. ---------- For Example: - https://answers.unity.com/questions/993523/how-to-make-a-shop-system.html - https://answers.unity.com/questions/1904005/a-native-collection-has-not-been-disposed-resultin-1.html - At first, I thought that this relates to some very advanced and complicated stuff. But then I see a question about a simple feature like TextMeshPro, again having this t$$anonymous$$s: https://answers.unity.com/questions/1934516/textmeshpro-2.html ---------- Can someone please spare a few minutes to reply to what this is? Thanks for your time :)