What is a div overlay?

from my limited knowledge

a <div>

is a tag used to make a "division" in the webpage (like tables but cleaner)

the beauty of the <div> is that it doesn't have any visual effects as just <div>

so it is perfect to use with css

(<div class="name">}

the Word "class" would be represented in css as .

and name would show as .name

meaning you can set the height, width, colour, style, font etc.. for content that appears inside that div.