Bootstrap is a popular HTML, CSS, and JS framework for developing responsive, mobile first project on the web.
 
Basic template 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 <!DOCTYPE html> <html  lang ="en" >   <head >      <meta  charset ="utf-8" >      <meta  http-equiv ="X-UA-Compatible"  content ="IE=edge" >      <meta  name ="viewport"  content ="width=device-width, initial-scale=1" >           <title > Bootstrap 101 Template</title >           <link  href ="css/bootstrap.min.css"  rel ="stylesheet" >                      <script src="https://oss.maxcdn.com/html5shiv/3.7.2/html5shiv.min.js"></script>       <script src="https://oss.maxcdn.com/respond/1.4.2/respond.min.js"></script>     <![endif]-->    </head >    <body >      <h1 > Hello, world!</h1 >           <script  src ="https://ajax.googleapis.com/ajax/libs/jquery/1.11.3/jquery.min.js" > </script >           <script  src ="js/bootstrap.min.js" > </script >    </body >  </html > 
 
Overview HTML5 doctype 1 2 3 4 <!DOCTYPE HTML> <html  lang ="en" >   ... </html > 
 
Mobile first 1 2 3 <meta  name ="viewport"  content ="width=device-width, initial-scale=1" >   OR disable zooming <meta  name ="viewport"  content ="width=device-width, initial-scale=1, maximum-scale=1, user-scalable=no" > 
 
Containers 1 2 3 4 5 6 7 8 9 responsive fixed width container <div  class ="container" >   ... </div > full width container, spanning the entire width of your viewport <div  class ="container-fluid" >   ... </div > 
 
Grid system Example: Mobile,tablet,desktop 1 2 3 4 5 6 7 8 9 10 11 <div  class ="row" >   <div  class ="col-xs-12 col-sm-6 col-md-8" > .col-xs-12 .col-sm-6 .col-md-8</div >    <div  class ="col-xs-6 col-md-4" > .col-xs-6 .col-md-4</div >  </div > <div  class ="row" >   <div  class ="col-xs-6 col-sm-4" > .col-xs-6 .col-sm-4</div >    <div  class ="col-xs-6 col-sm-4" > .col-xs-6 .col-sm-4</div >       <div  class ="clearfix visible-xs-block" > </div >    <div  class ="col-xs-6 col-sm-4" > .col-xs-6 .col-sm-4</div >  </div > 
 
Fluid container 1 2 3 4 5 <div  class ="container-fluid" >   <div  class ="row" >      ...   </div >  </div > 
 
Offsetting columns 1 2 3 4 <div  class ="row" >   <div  class ="col-md-3 col-md-offset-3" > .col-md-3 .col-md-offset-3</div >    <div  class ="col-md-3 col-md-offset-3" > .col-md-3 .col-md-offset-3</div >  </div > 
 
Typography Headings 1 2 <h1 > h1. Bootstrap heading <small > Secondary text</small > </h1 > <h4 > h4. Bootstrap heading <small > Secondary text</small > </h4 > 
 
Lead body copy  
Inline text elements 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 Marked text You can use the mark tag to <mark > highlight</mark >  text. Deleted text <del > This line of text is meant to be treated as deleted text.</del > Strikethrough text <s > This line of text is meant to be treated as no longer accurate.</s > Inserted text <ins > This line of text is meant to be treated as an addition to the document.</ins > Underlined text <u > This line of text will render as underlined</u > Small text <small > This line of text is meant to be treated as fine print.</small > Bold or <b >  <strong > rendered as bold text</strong > Italics or <i >  <em > rendered as italicized text</em > 
 
Alignment classes 1 2 3 4 5 <p  class ="text-left" > Left aligned text.</p > <p  class ="text-center" > Center aligned text.</p > <p  class ="text-right" > Right aligned text.</p > <p  class ="text-justify" > Justified text.</p > <p  class ="text-nowrap" > No wrap text.</p > 
 
1 2 3 <p  class ="text-lowercase" > Lowercased text.</p > <p  class ="text-uppercase" > Uppercased text.</p > <p  class ="text-capitalize" > Capitalized text.</p > 
 
Abbreviations 1 2 3 <abbr  title ="attribute" > attr</abbr > <abbr  title ="HyperText Markup Language"  class ="initialism" > HTML</abbr > 
 
Address 1 2 3 4 5 6 7 8 9 10 11 <address >   <strong > Twitter, Inc.</strong > <br >    1355 Market Street, Suite 900<br >    San Francisco, CA 94103<br >    <abbr  title ="Phone" > P:</abbr >  (123) 456-7890 </address > <address >   <strong > Full Name</strong > <br >    <a  href ="mailto:#" > first.last@example.com</a >  </address > 
 
Blockquotes 1 2 3 4 <blockquote >   <p > Lorem ipsum dolor sit amet, consectetur adipiscing elit. Integer posuere erat a ante.</p >    <footer > Someone famous in <cite  title ="Source Title" > Source Title</cite > </footer >  </blockquote > 
 
Lists 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 Unstyled <ul  class ="list-unstyled" >   <li > ...</li >  </ul > Inline <ul  class ="list-inline" >   <li > ...</li >  </ul > Horizontal description <dl  class ="dl-horizontal" >   <dt > ...</dt >    <dd > ...</dd >  </dl > 
 
Code Inline 1 For example, <code > <section></code >  should be wrapped as inline. 
 
1 2 To switch directories, type <kbd > cd</kbd >  followed by the name of the directory.<br >  To edit settings, press <kbd > <kbd > ctrl</kbd >  + <kbd > ,</kbd > </kbd >  
 
Basic block 1 2 3 <pre > <p>Sample text here...</p></pre > <pre  class ="pre-scrollabe" > </pre > 
 
Variables 1 <var > y</var >  = <var > m</var > <var > x</var >  + <var > b</var > 
 
Sample output 1 <samp > This text is meant to be treated as sample output from a computer program.</samp > 
 
Basic example1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 <form >   <div  class ="form-group" >      <label  for ="exampleInputEmail1" > Email address</label >      <input  type ="email"  class ="form-control"  id ="exampleInputEmail1"  placeholder ="Email" >    </div >    <div  class ="form-group" >      <label  for ="exampleInputPassword1" > Password</label >      <input  type ="password"  class ="form-control"  id ="exampleInputPassword1"  placeholder ="Password" >    </div >    <div  class ="form-group" >      <label  for ="exampleInputFile" > File input</label >      <input  type ="file"  id ="exampleInputFile" >      <p  class ="help-block" > Example block-level help text here.</p >    </div >    <div  class ="checkbox" >      <label >        <input  type ="checkbox" >  Check me out     </label >    </div >    <button  type ="submit"  class ="btn btn-default" > Submit</button >  </form > 
Tables Striped rows1 2 3 <table  class ="table table-striped" >   ... </table > 
Hover rows1 2 3 4 5 6 <table  class ="table table-hover" >   ...   <tr >      <td  class ="info" > ...</td >    </tr >  </table > 
Button tags: <a>,<button>,<input>1 2 3 4 <a  class ="btn btn-default"  href ="#"  role ="button" > Link</a > <button  class ="btn btn-default"  type ="submit" > Button</button > <input  class ="btn btn-default"  type ="button"  value ="Input" > <input  class ="btn btn-default"  type ="submit"  value ="Submit" > 
Options & Sizes1 2 3 4 5 6 7 <p >   <button  type ="button"  class ="btn btn-primary btn-sm" > Large button</button >    <button  type ="button"  class ="btn btn-default btn-lg" > Large button</button >  </p > <button  type ="button"  class ="btn btn-info btn-lg btn-block" > Block level button</button > <button  type ="button"  class ="btn btn-danger btn-lg btn-block" > Block level button</button > 
Images Responsive images1 <img  src ="..."  class ="img-responsive"  alt ="Responsive image" > 
Image shapes1 2 3 <img  src ="..."  alt ="..."  class ="img-rounded" > <img  src ="..."  alt ="..."  class ="img-circle" > <img  src ="..."  alt ="..."  class ="img-thumbnail" > 
Helper classes Contextual colors & Contextual backgrounds1 2 3 4 5 <p  class ="text-muted" > ...</p > <p  class ="text-primary" > ...</p > <p  class ="bg-warning" > ...</p > <p  class ="bg-danger" > ...</p > 
Close icon1 <button  type ="button"  class ="close"  aria-label ="Close" > <span  aria-hidden ="true" > ×</span > </button > 
Carets1 <span  class ="caret" > </span > 
Showing and hiding content1 2 <div  class ="show" > ...</div > <div  class ="hidden" > ...</div > 
Responsive utilities .visible-sm-*,.hidden-md,visible-*-inline