How are link previews displayed in social networks?

Question

Browsers

Hello everyone) Now I asked myself this question "Why in TG (I don’t know about VK) some links display previews, and some do not? I typed in Google, but did not get the result. If someone can, then direct me to the article, I will I want to understand - how it works in Telegram, or if it depends on the site itself - what does it have that allows you to show previews?

If so, then both links start with "https:// "

I think you won't really need screenshots, but just in case, I'll add:

Answer 1

https://ruogp.me/

Answer 2

I also advise you to read about Open Graph and use the facebook and vkontakte debuggers, they will help you solve problems, especially with images.