What does appendchild command do?

Answer 1

appendChild is used to append a child in a html element. eg.
If we have a <ol> list with three list <li> items, and using JS, if we need to add one more <li> element, then we can use appendChild.

Answer 2

appends a new html element into the parent element
https://www.sololearn.com/learn/JavaScript/2755/