In the last exercise of this section the element requires # before its name. Why is this not mentioned anywhere in CSS lessons?

Question

Finally had to ask for a hint. For some reason an explanation is not readily available in the lesson as to why the id needs a hash-tag before its name. Perhaps I'm missing something, which is why any advice on this issue would be appreciated.

Answer 1

Paul Ottwell u should check out the 3rd slide in this lesson :
https://www.sololearn.com/learn/CSS/1080/