A floating element is one where the computed value of float is not none.

As float implies the use of the block layout, it modifies the computed value of the display values, in some cases:

/* Keyword values */
float: left;
float: right;
float: none;
float: inline-start;
float: inline-end;

/* Global values */
float: inherit;
float: initial;
float: revert;
float: revert-layer;
float: unset;

The float property is specified as a single keyword, chosen from the list of values below.

left

The element must float on the left side of its containing block.

right

The element must float on the right side of its containing block.

none

The element must not float.

inline-start

The element must float on the start side of its containing block. That is the left side with ltr scripts, and the right side with rtl scripts.

inline-end

The element must float on the end side of its containing block. That is the right side with ltr scripts, and the left side with rtl scripts.

float = 
  block-start      |
  block-end        |
  inline-start     |
  inline-end       |
  snap-block       |
  <snap-block()>   |
  snap-inline      |
  <snap-inline()>  |
  left             |
  right            |
  top              |
  bottom           |
  none             |
  footnote         

<snap-block()> = 
  snap-block( <length> , [ start | end | near ]? )  

<snap-inline()> = 
  snap-inline( <length> , [ left | right | near ]? )  

As mentioned above, when an element is floated, it is taken out of the normal flow of the document (though still remaining part of it). It is shifted to the left, or right, until it touches the edge of its containing box, or another floated element.

In this example, there are three colored squares. Two are floated left, and one is floated right. Note that the second "left" square is placed to the right of the first. Additional squares would continue to stack to the right, until they filled the containing box, after which they would wrap to the next line.

A floated element is at least as tall as its tallest nested floated children. We gave the parent width: 100% and floated it to ensure it is tall enough to encompass its floated children, and to make sure it takes up the width of the parent so we don't have to clear its adjacent sibling.

HTML

<section>
  <div class="left">1</div>
  <div class="left">2</div>
  <div class="right">3</div>
  <p>Lorem ipsum dolor sit amet, consectetur adipiscing elit.
     Morbi tristique sapien ac erat tincidunt, sit amet dignissim
     lectus vulputate. Donec id iaculis velit. Aliquam vel
     malesuada erat. Praesent non magna ac massa aliquet tincidunt
     vel in massa. Phasellus feugiat est vel leo finibus congue.</p>
</section>

CSS

section {
  box-sizing: border-box;
  border: 1px solid blue;
  width: 100%;
  float: left;
}

div {
  margin: 5px;
  width: 50px;
  height: 150px;
}

.left {
  float: left;
  background: pink;
}

.right {
  float: right;
  background: cyan;
}

Result

Sometimes you may want to force an item to move below any floated elements. For instance, you may want paragraphs to remain adjacent to floats, but force headings to be on their own line. See clear for examples.

• Block formatting context
• Use clear to force an item to move below a floated element.