To vertically center a `div` in the body of HTML, you can use either Flexbox or CSS Grid:
*Flexbox:*
css
body {
display: flex;
align-items: center;
justify-content: center;
height: 100vh;
margin: 0;
}
*CSS Grid:*
css
body {
display: grid;
place-items: center;
height: 100vh;
margin: 0;
}