https://www.w3schools.com/tags/tag_div.asp HTML <div> Tag.

defines a division or a section in an HTML document ... used to group block-elements to format them with CSS.

Besides its uses as a CSS grouper you may also see it used in a named fashon in javascript as a lvalue or rvalue

 a = document.getElementById("tableId").innerHTML;
...
 parent.document.getElementById("tableId").innerHTML = a;
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