Why Html <marquee> is not included in sololearn

Answer 1

I believe you meant <marquee>
Yes, it is not included as it is considered an obsolet element and should no longer be used. But you can use CSS and Javascript to create similar effects.

Answer 2

Documentation says that it is not recommended to use <marquee> and use CSS instead. The tag became obsolete. That's why it's not included.

Answer 3

Using marquee is a fundamental element if you want to master making the most annoying to read website ever. I had a friend who attempted to do that a long time ago. It was the most terrible and amazing thing you could imagine.