<param> is to define which element

Answer 1

https://www.w3schools.com/TAGS/tag_param.asp
This should help. Also make sure you check other sources before posting. 😊

Answer 2

Parameters with the Object element

Answer 3

html:
do i understand <param>that right: </param>

css:
p::selection {
color:red
}

now „that right“ is red?