BLOCK
Div align center specifies the horizontal alignment of the content inside web site.
code:
<!DOCTYPE html>
<html>
<header>
<style>
.content {
background-color:silver;
}
.block {
width:50%;
height:200px;
background-color:red;
}
</style>
</header>
<body>
<div class="content">
<br>
<div align="center">
<div class="block">
<p>BLOCK</p>
</div>
<br>
</div>
</div>
</body>
</html>
result:
BLOCK