Difference Between Style = "Position:Absolute" and Style = "Position:Relative"

Difference between style = position:absolute and style = position:relative

Absolute positioning means that the element is taken completely out of the normal flow of the page layout. As far as the rest of the elements on the page are concerned, the absolutely positioned element simply doesn't exist. The element itself is then drawn separately, sort of "on top" of everything else, at the position you specify using the left, right, top and bottom attributes.

Using the position you specify with these attributes, the element is then placed at that position within its last ancestor element which has a position attribute of anything other than static (page elements default to static when no position attribute specified), or the document body (browser viewport) if no such ancestor exists.

For example, if I had this code:

<body>
  <div style="position:absolute; left: 20px; top: 20px;"></div>
</body>

...the <div> would be positioned 20px from the top of the browser viewport, and 20px from the left edge of same.

However, if I did something like this:

 <div id="outer" style="position:relative">
   <div id="inner" style="position:absolute; left: 20px; top: 20px;"></div>
 </div>

...then the inner div would be positioned 20px from the top of the outer div, and 20px from the left edge of same, because the outer div isn't positioned with position:static because we've explicitly set it to use position:relative.

Relative positioning, on the other hand, is just like stating no positioning at all, but the left, right, top and bottom attributes "nudge" the element out of their normal layout. The rest of the elements on the page still get laid out as if the element was in its normal spot though.

For example, if I had this code:

<span>Span1</span>
<span>Span2</span>
<span>Span3</span>

...then all three <span> elements would sit next to each other without overlapping.

If I set the second <span> to use relative positioning, like this:

<span>Span1</span>
<span style="position: relative; left: -5px;">Span2</span>
<span>Span3</span>

...then Span2 would overlap the right side of Span1 by 5px. Span1 and Span3 would sit in exactly the same place as they did in the first example, leaving a 5px gap between the right side of Span2 and the left side of Span3.

Hope that clarifies things a bit.

Position Relative vs Absolute?

Absolute CSS Positioning

position: absolute;

Absolute positioning is the easiest to understand. You start with the CSS position property:

position: absolute;

This tells the browser that whatever is going to be positioned should be removed from the normal flow of the document and will be placed in an exact location on the page. It won't affect how the elements before it or after it in the HTML are positioned on the Web page however it will be subject to it's parents' positioning unless you override it.

If you want to position an element 10 pixels from the top of the document window, you would use the top offset to position it there with absolute positioning:

position: absolute;
top: 10px;

This element will then always display 10px from the top of the page regardless of what content passes through, under or over the element (visually).

The four positioning properties are:

top
right
bottom
left

To use them, you need to think of them as offset properties. In other words, an element positioned right: 2px is not moved right 2px. It's right side is offset from the right side of the window (or its position overriding parent) by 2px. The same is true for the other three.

Relative Positioning

position: relative;

Relative positioning uses the same four positioning properties as absolute positioning. But instead of basing the position of the element upon the browser view port, it starts from where the element would be if it were still in the normal flow.

For example, if you have three paragraphs on your Web page, and the third has a position: relative style placed on it, its position will be offset based on its current location-- not from the original sides of the view port.

Paragraph 1.

Paragraph 2.

Paragraph 3.

In the above example, the third paragraph will be positioned 3em from the left side of the container element, but will still be below the first two paragraphs. It would remain in the normal flow of the document, and just be offset slightly. If you changed it to position: absolute;, anything following it would display on top of it, because it would no longer be in the normal flow of the document.

Notes:

the default width of an element that is absolutely positioned is the width of the content within it, unlike an element that is relatively positioned where it's default width is 100% of the space it can fill.
You can have elements that overlap with absolutely positioned elements, whereas you cannot do this with relatively positioned elements (natively i.e without the use of negative margins/positioning)

lots pulled from: this resource

CSS relative vs absolute position

If you use position:absolute but don't set top, left, bottom or right, the element takes the position it would have had in normal flow, even though it is not itself in normal flow, so doesn't affect the position of subsequent elements.

So if you change an element without top, left, bottom or right from absolute to relative it doesn't move, this is it still takes it's place in normal flow, but it is now in normal flow, so subsequent elements will move to take account of its size.

CSS position relative and absolute

relative positioning keeps elements on the page so their position is affected by other static and relative positioned elements. If you want the black box to be positioned relative to the yellow box, you want to make the black box position: absolute. An absolutely positioned element will be positioned relative to it's closest non-static positioned ancestor.

<!DOCTYPE html><html>
<head>  <title></title></head>
<body>  <div style="position: absolute;left:100px;top: 100px;height:600px;background-color: yellow;width: 600px;">    <div style="position:relative;left:100px;top:100px;height:200px;width:500px;background-color: red;">    </div>    <div style="position:absolute;left:100px;top:50px;height:10px;width:10px;background-color: black;">    </div>  </div></body>
</html>

I don't understand absolute and relative positioning in CSS

Absolute positioning means that the element is taken completely out of the normal flow of the page layout. As far as the rest of the elements on the page are concerned, the absolutely positioned element simply doesn't exist. The element itself is then drawn separately, sort of "on top" of everything else, at the position you specify using the left, right, top and bottom attributes.

Using the position you specify with these attributes, the element is then placed at that position within it's last ancestor element which has a position attribute of anything other than static (static is the positioning elements use if they have no position attribute specified), or the document body (browser viewport) if no such ancestor exists.

For example, if I had this code:

<body>
  <div style="position:absolute; left: 20px; top: 20px;"></div>
</body>...then the <div> would be positioned 20 px from the top of the browser viewport, and 20px from the left edge of same.

However, if I did something like this:

<div id="outer" style="position:relative">
   <div id="inner" style="position:absolute; left: 20px; top: 20px;"></div>
 </div>...

then the inner div would be positioned 20px from the top of the outer div, and 20px from the left edge of same, because the outer div isn't positioned with position:static because we've explicitly set it to use position:relative.

Relative positioning, on the other hand, is just like stating no positioning at all, but the left, right, top and bottom attributes "nudge" the element out of their normal layout. The rest of the elements on the page still get laid out as if the element was in its normal spot though.

For example, if I had this code:

<span>Span1</span>
<span>Span2</span>
<span>Span3</span>...

then all three elements would sit next to each other without overlapping.

If I set the second to use relative positioning, like this:

<span>Span1</span>
<span style="position: relative; left: -5px;">Span2</span>
<span>Span3</span>...

then Span2 would overlap the right side of Span1 by 5px. Span1 and Span3 would sit in exactly the same place as they did in the first example, leaving a 5px gap between the right side of Span2 and the left side of Span3.

Hope that clarifies things a bit

For more details refer to this: http://css-tricks.com/absolute-relative-fixed-positioining-how-do-they-differ/

This is also a good one : http://sitepoint.refererence.sitepoint.com

Understanding relative position in css

"Normal position" is in the context of the DOM, and refers to Normal flow:

First of all, individual element boxes are laid out by taking the elements' content, then adding any padding, border and margin around them.
By default, a block level element's content is 100% of the width of its parent element, and as tall as its content. Inline elements are as tall as their content, and as wide as their content.

This is explained in further detail in the CSS flow layout:

Normal Flow, or Flow Layout, is the way that Block and Inline elements are displayed on a page before any changes are made to their layout. The flow is essentially a set of things that are all working together and know about each other in your layout. Once something is taken out of flow it works independently.
In normal flow, inline elements display in the inline direction, that is in the direction words are displayed in a sentence according to the Writing Mode of the document. Block elements display one after the other, as paragraphs do in the Writing Mode of that document. In English therefore, inline elements display one after the other, starting on the left, and block elements start at the top and move down the page.

It's worth noting that all elements have static positioning by default:

Static positioning is the default that every element gets — it just means "put the element into its normal position in the document layout flow — nothing special to see here."

And relative positioning simply allows for modification of the position:

This is very similar to static positioning, except that once the positioned element has taken its place in the normal layout flow, you can then modify its final position.

Difference Between Style = "Position:Absolute" and Style = "Position:Relative"