这很简单。

span的使用不会影响布局，因为它是内联的(在行中(不应该混淆，因为东西可以被换行)) 使用div会影响布局，里面的内容会出现在新行(block element)中，当你想添加的元素没有特殊的语义，而你想让它出现在新行中时，使用<div>。

<div>是块级元素，<span>是行内元素。

如果你想对一些内联文本做一些事情，<span>是正确的选择，因为它不会像<div>那样引入换行符。

正如其他人所注意到的，这些都隐含着一些语义，最重要的事实是，<div>暗示了文档中的逻辑划分，类似于文档的一个部分或其他内容，例如:

<div id="Chapter1">
   <p>Lorem ipsum dolor sit amet, <span id="SomeSpecialText1">consectetuer adipiscing</span> elit. Duis congue vehicula purus.</p>
   <p>Nam <span id="SomeSpecialText2">eget magna nec</span> sapien fringilla euismod. Donec hendrerit.</p> 
</div>

为了完整起见，我建议你这样思考:

There are lots of block elements (linebreaks before and after) defined in HTML, and lots of inline tags (no linebreaks). But in modern HTML all elements are supposed to have meanings: a <p> is a paragraph, an <li> is a list item, etc., and we're supposed to use the right tag for the right purpose -- not like in the old days when we indented using <blockquote> whether the content was a quote or not. So, what do you do when there is no meaning to the thing you're trying to do? There's no meaning to a 400px-wide column, is there? You just want your column of text to be 400px wide because that suits your design. For this reason, they added two more elements to HTML: the generic, or meaningless elements <div> and <span>, because otherwise, people would go back to abusing the elements which do have meanings.

真正重要的区别已经在克里斯的回答中提到了。然而，这并不是对每个人都有明显的影响。

作为一个内联元素，<span>只能包含其他内联元素。因此下面的代码是错误的:

<span><p>This is a paragraph</p></span>

上面的代码无效。要包装块级元素，必须使用另一个块级元素(例如<div>)。另一方面，<div>只能在块级元素合法的地方使用。

此外，这些规则在(X)HTML中是固定的，它们不会因CSS规则的存在而改变!所以下面的代码也是错的!

<span style="display: block"><p>Still wrong</p></span>
<span><p style="display: inline">Just as wrong</p></span>

Div是一个块元素 Span是一个内联元素。

这意味着要在语义上使用它们，div应该用于包装文档的各个部分，而span应该用于包装文本、图像等小部分。

例如:

<div>This a large main division, with <span>a small bit</span> of spanned text!</div>

注意，在内联元素中放置块级元素是非法的，因此:

<div>Some <span>text that <div>I want</div> to mark</span> up</div>

.．.是非法的。

编辑:从HTML5开始，一些块元素可以放在一些内联元素中。请参阅这里的MDN参考，以获得相当清晰的清单。以上仍然是非法的，因为<span>只接受短语内容，而<div>是流内容。

你要求一些具体的例子，所以这是一个从我的保龄球网站，BowlSK:

< div id = "头" > < div id = " userbar " > 嗨，大家好，<span class="username">Chris Marasti-Georg</span> | <a href="/edit-profile.html">Profile</a> | .html < a href = " https://www.bowlsk.com/_ah/logout?..。“>签署< / > < / div > < h1 > < a href = " / " >碗<跨类= >“sk sk < / span > < / > < / h1 > < / div >

Ok, what's going on? At the top of my page, I have a logical section, the "header". Since this is a section, I use a div (with an appropriate id). Within that, I have a couple of sections: the user bar and the actual page title. The title uses the appropriate tag, h1. The userbar, being a section, is wrapped in a div. Within that, the username is wrapped in a span, so that I can change the style. As you can see, I have also wrapped a span around 2 letters in the title - this allows me to change their color in my stylesheet.

还要注意的是，HTML5包含了一组广泛的新元素，这些元素定义了常见的页面结构，如article、section、nav等。

Section 4.4 of the HTML 5 working draft lists them and gives hints as to their usage. HTML5 is still a working spec, so nothing is "final" yet, but it is highly doubtful that any of these elements are going anywhere. There is a javascript hack that you will need to use if you want to style these elements in some older version of IE - You need to create one of each element using document.createElement before any of those elements are specified in your source. There are a bunch of libraries that will take care of this for you - a quick Google search turned up html5shiv.

正如在其他回答中提到的，默认情况下div将被呈现为块元素，而span将在其上下文中内联呈现。但两者都没有任何语义价值;它们的存在允许您对任何给定的内容应用样式和标识。使用样式，可以使div像span一样，反之亦然。

div的一个有用的样式是内联块

例子:

http://dustwell.com/div-span-inline-block.html CSS显示:内联vs内联块

我曾在游戏网页项目中使用内联块取得了巨大的成功。