This is for Text Centering (which is what the question was about)

For other types of content, see Flavien's answer.

Update: Bootstrap 2.3.0+ Answer

The original answer was for an early version of bootstrap. As of bootstrap 2.3.0, you can simply give the div the class .text-center.

Original Answer (pre 2.3.0)

You need to define one of the two classes, row or span12 with a text-align: center. See http://jsfiddle.net/xKSUH/ or http://jsfiddle.net/xKSUH/1/

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NOTE: this was removed in Bootstrap 3.

Pre-Bootstrap 3, you could use the CSS class pagination-centered like this:

<div class="span12 pagination-centered">
    Centered content.
</div>

Class pagination-centered is already in bootstrap.css (or bootstrap.min.css) and has the only one rule:

.pagination-centered{text-align:center;}

With Bootstrap 2.3.0. just use class text-center

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I guess most of the people here are actually searching for the way to center the whole div and not only the text content (which is trivial…).

The second way (instead of using text-align:center) to center things in HTML is to have an element with a fixed width and auto margin (left and right). With Bootstrap, the style defining auto margins is the "container" class.

<div class="container">
    <div class="span12">
        "Centered stuff there"
    </div>
</div>

Take a look here for a fiddle: http://jsfiddle.net/D2RLR/7788/

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Bootstrap 5 (update 2021)

Bootstrap 5 still uses flexbox grid layout, so centering works the same way.

text-center to center display:inline elements (ie: span, img)

mx-auto for centering inside flex elements

offset-* or mx-auto can be used to center columns (.col-)

justify-content-center to center columns (col-*) inside row

Bootstrap 4

"Centered content" can mean many different things, and Bootstrap centering has changed a lot since the original post.

Horizontal Center

Bootstrap 3

text-center is used for display:inline elements

center-block to center display:block elements

col-*offset-* to center grid columns

see this answer to center the navbar

Demo Bootstrap 3 Horizontal Centering

Bootstrap 4

text-center is still used for display:inline elements

mx-auto replaces center-block to center display:block elements

offset-* or mx-auto can be used to center grid columns

justify-content-center in row can also be used to center col-*

mx-auto (auto x-axis margins) will center display:block or display:flex elements that have a defined width, (%, vw, px, etc..). Flexbox is used by default on grid columns, so there are also various flexbox centering methods.

Demo Bootstrap 4 Horizontal Centering

Now that Bootstrap 4 is flexbox by default there are many different approaches to vertical alignment using: auto-margins, flexbox utils, or the display utils along with vertical align utils. At first "vertical align utils" seems obvious but these only work with inline and table display elements. Here are some Bootstrap 4 vertical centering options..

1 - Vertical Center Using Auto Margins:

Another way to vertically center is to use my-auto. This will center the element within it's container. For example, h-100 makes the row full height, and my-auto will vertically center the col-sm-12 column.

<div class="row h-100">
    <div class="col-sm-12 my-auto">
        <div class="card card-block w-25">Card</div>
    </div>
</div>

Vertical Center Using Auto Margins Demo

my-auto represents margins on the vertical y-axis and is equivalent to:

margin-top: auto;
margin-bottom: auto;

2 - Vertical Center with Flexbox:

https://i.stack.imgur.com/gKaKI.png

Since Bootstrap 4 .row is now display:flex you can simply use align-self-center on any column to vertically center it...

       <div class="row">
           <div class="col-6 align-self-center">
                <div class="card card-block">
                 Center
                </div>
           </div>
           <div class="col-6">
                <div class="card card-inverse card-danger">
                    Taller
                </div>
          </div>
    </div>

or, use align-items-center on the entire .row to vertically center align all col-* in the row...

       <div class="row align-items-center">
           <div class="col-6">
                <div class="card card-block">
                 Center
                </div>
           </div>
           <div class="col-6">
                <div class="card card-inverse card-danger">
                    Taller
                </div>
          </div>
    </div>

Vertical Center Different Height Columns Demo

3 - Vertical Center Using Display Utils:

Bootstrap 4 has display utils that can be used for display:table, display:table-cell, display:inline, etc.. These can be used with the vertical alignment utils to align inline, inline-block or table cell elements.

<div class="row h-50">
    <div class="col-sm-12 h-100 d-table">
        <div class="card card-block d-table-cell align-middle">
            I am centered vertically
        </div>
    </div>
</div>

Vertical Center Using Display Utils Demo

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Bootstrap 3.1.1 has a .center-block class for centering divs. See: http://getbootstrap.com/css/#helper-classes-center.

Center content blocks Set an element to display: block and center via margin. Available as a mixin and class.

<div class="center-block">...</div>

Or, as others have already said, use the .text-center class to centre text.

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The best way to do this is define a css style:

.centered-text {
    text-align:center
}    

Then where ever you need centered text you add it like so:

<div class="row">
    <div class="span12 centered-text">
        <h1>Bootstrap starter template</h1>
        <p>Use this document as a way to quick start any new project.<br> All you get is this message and a barebones HTML document.</p>
    </div>
</div>

or if you just want the p tag centered:

<div class="row">
    <div class="span12 centered-text">
        <h1>Bootstrap starter template</h1>
        <p class="centered-text">Use this document as a way to quick start any new project.<br> All you get is this message and a barebones HTML document.</p>
    </div>
</div>

The less inline css you use the better.

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The class .show-grid is applying center aligned text in the example in the link.

You can always add style="text-align:center" to your row div or some other class I would think.

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As of February 2013, in some cases, I add a "centred" class to the "span" div:

<div class="container">
  <div class="row">
    <div class="span9 centred">
      This div will be centred.
    </div>
  </div>
</div>

and to CSS:

[class*="span"].centred {
  margin-left: auto;
  margin-right: auto;
  float: none;
}

The reason for this is because the span* div's get floated to the left, and the "auto margin" centering technique works only if the div is not floated.

Demo (on JSFiddle): http://jsfiddle.net/5RpSh/8/embedded/result/

JSFiddle: http://jsfiddle.net/5RpSh/8/

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If you use Bootstrap 3, it also has built-in CSS class named .text-center. That's what you want.

<div class="text-left">
    left
</div>

<div class="text-center">
    center
</div>

<div class="text-right">
    right
</div>

Please see the example in jsfiddle. http://jsfiddle.net/ucheng/Q4Fue/

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Bootstrap 2.3 has a text-center class.

<p class="text-left">Left aligned text.</p>
<p class="text-center">Center aligned text.</p>
<p class="text-right">Right aligned text.</p>

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On my side I define new CSS styles ready to use and easy to remember:

.center { text-align: center;}
.left { text-align: left;}
.right { text-align: right;}
.justify { text-align: justify;}
.fleft { float: left;} /*-> similar to .pull-left already existing in bootstrap*/
.fright { float: right;}  /*-> similar to .pull-right already existing in bootstrap*/
.vab { vertical-align: bottom;}
.bold { font-weight: bold;}
.italic { font-style: italic;}

Is it a good idea? Is there any good practice for this?

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If you are using Bootstrap 2.0+

This can make the div centered to the page.

<div class="row">
    <div class="span4 offset4">
        //your content here gets centered of the page
    </div>
</div>

---

Any text-align utility class would do the trick. Bootstrap has been using .text-center class for centering text for a long time now.

.text-center { text-align: center !important; }

Or you can create your own utilities. Some variations I've seen over the years:

.u-text-center { text-align: center !important; }
.ta-center { text-align: center !important; }
.ta\:c { text-align: center !important; }

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You need to adjust with the .span.

Example:

<div class="container-fluid">
  <div class="row-fluid">
    <div class="span4"></div>
    <!--/span-->
    <div class="span4" align="center">
      <div class="hero-unit" align="center">
        <h3>Sign In</h3>
        <form>
          <div class="input-prepend">
            <span class="add-on"><i class="icon-envelope"></i> </span>
            <input class="span6" type="text" placeholder="Email address">
          </div>
          <div class="input-prepend">
            <span class="add-on"><i class="icon-key"></i> </span>
            <input class="span6" type="password" placeholder="Password">
          </div>
        </form>
      </div>
    </div>
    <!-- /span -->
    <div class="span4"></div>
  </div>
  <!-- /row -->
</div>

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My preferred method for centering blocks of information while maintaining responsiveness (mobile compatibility) is to place two empty span1 divs before and after the content you wish to center.

<div class="row-fluid">

    <div class="span1">
    </div>

        <div class="span10">
          <div class="hero-unit">
            <h1>Reading Resources</h1>
            <p>Read here...</p>
          </div>
        </div><!--/span-->

    <div class="span1">
    </div>

</div><!--/row-->

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For Bootstrap version 3.1.1 and above, the best class for centering the content is the .center-block helper class.

---

<div class="container">
  <div class="col-md-12 centered">
    <div class="row">
      <div class="col-md-1"></div>
       <div class="col-md-10">
           label
       </div>
      <div class="col-md-1"></div>
    </div>
  </div>
</div>

Do not use container-fluid in the main.

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Center-block is also an option not referred in above answers

    <div class="center-block" style="width:200px;background-color:#ccc;">...</div>

All the class center-block does is to tell the element to have a margin of 0 auto, the auto being the left/right margins. However, unless the class text-center or css text-align:center; is set on the parent, the element does not know the point to work out this auto calculation from, so it will not center itself as anticipated.

So text-center is a better option.

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You can use any one of the below types

Use the Bootstrap existing class text-center. Adding a custom style, style = "text-align:center". Use a column offset: Example:

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I created this class to keep the centered regardless of screen size while maintaining responsive features:

.container {
    alignment-adjust: central;
}

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Simply use a class, text-center, for the div or tag which you want. I think it may work fine. It is a Bootstrap class for text align center.

Here are some text alignment Bootstrap classes:

text-left, text-right, text-justify, etc.
<div class="row">
 <div class="col-md-12 text-center">
  <h1>Bootstrap starter template</h1>
  <p>Example text.</p>
 </div>
</div>

---

I tried two ways, and it worked fine to center the div. Both the ways will align the divs on all screens.

Way 1: Using Push:

<div class = "col-lg-4 col-md-4 col-sm-4 col-xs-4 col-lg-push-4 col-md-push-4 col-sm-push-4 col-xs-push-4" style="border-style:solid;border-width:1px">
    <h2>Grievance form</h2> <!-- To center this text, use style="text-align: center" -->
  </div>

Way 2: Using Offset:

<div class = "col-lg-4 col-md-4 col-sm-4 col-xs-4 col-lg-offset-4 col-md-offest-4 col-sm-offest-4 col-xs-offest-4" style="border-style:solid;border-width:1px">
    <h2>Grievance form</h2> <!--to center this text, use style="text-align: center"-->
</div>

Result:

https://i.stack.imgur.com/VPegx.png

Explanation

Bootstrap will designate to the left, the first column of the specified screen-occupancy. If we use offset or push it will shift the 'this' column by 'those' many columns. Though I faced some issues in responsiveness of offset, push was awesome.

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Update 2018:

In Bootstrap 4.1.3, content can be centered using class mx-auto.

<div class="mx-auto">
  Centered element
</div>

Reference: https://getbootstrap.com/docs/4.1/utilities/spacing/#horizontal-centering

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