摘要：和的區(qū)別，可以從三個(gè)層次上來談。首先看中的說明表示強(qiáng)調(diào)，表示更強(qiáng)烈的強(qiáng)調(diào)。言簡意賅，表明了和的命名來歷。并且在瀏覽器中，默認(rèn)用斜體表示，用粗體表示。強(qiáng)調(diào)事實(shí)，討論的是貓是可愛的動物的事實(shí)。這里的使用是為了和其他內(nèi)容區(qū)分開來。

em 和 strong 的區(qū)別，可以從三個(gè)層次上來談。

首先看 HTML 4.01 中的說明：

EM: Indicates emphasis.
STRONG: Indicates stronger emphasis.

em 表示強(qiáng)調(diào)，strong 表示更強(qiáng)烈的強(qiáng)調(diào)。言簡意賅，表明了 em 和 strong 的命名來歷。并且在瀏覽器中，em 默認(rèn)用斜體表示，strong 用粗體表示。這是第一個(gè)層次上的區(qū)別。

第二個(gè)層次上，在 Emphasis in context versus overall highlighting 和 em vs. strong 這兩篇文章中，做了很好的總結(jié)：

  
em is for local emphasis. You see? Local emphasis. If you would emphasize a word in speech, use em. strong is for global highlighting.

  When somebody looks at your document, at a glance, certain words and phrases should jump out. These are the words and phrases that make up the gist of the content — the highlights.

em 用來局部強(qiáng)調(diào)，strong 則是全局強(qiáng)調(diào)。從視覺上考慮，em 的強(qiáng)調(diào)是有順序的，閱讀到某處時(shí)，才會注意到。strong 的強(qiáng)調(diào)則是一種隨意無順序的，看見某文時(shí)，立刻就凸顯出來的關(guān)鍵詞句。斜體和粗體剛好滿足了這兩種視覺效果，因此也就成了 em 和 strong 的默認(rèn)樣式。

感覺上面已經(jīng)解釋得很清楚了？我們再來看看第三個(gè)層次上的區(qū)別。HTML5 標(biāo)準(zhǔn)中做了詳盡解釋：

  
The em element represents stress emphasis of its contents.

  The placement of emphasis changes the meaning of the sentence.——em

  element
  
  
The strong element represents strong importance, seriousness, or urgency for its contents.
  
  
Importance: The strong element can be used in a heading, caption, or paragraph to distinguish the part that really matters from other parts that might be more detailed, more jovial, or merely boilerplate. (This is distinct from marking up subheadings, for which the hgroup element is appropriate.)
  
  
For example, the first word of the previous paragraph is marked up with strong to distinguish it from the more detailed text in the rest of the paragraph.
  
  
Seriousness: The strong element can be used to mark up a warning or caution notice.
  
  
Urgency: The strong element can be used to denote contents that the

  user needs to see sooner than other parts of the document.
  
  
The relative level of importance of a piece of content is given by its number of ancestor strong elements; each strong element increases the importance of its contents.
  
  
Changing the importance of a piece of text with the strong element does not change the meaning of the sentence.——strong element

em 表示內(nèi)容的重點(diǎn)（stress emphasis），strong 表示強(qiáng)烈的重要性、嚴(yán)重性或內(nèi)容的緊迫性，strong 不會改變所在句子的語意，em 則會改變所在句子的語義。并且舉了一個(gè)非常好的例子：

Cats are cute animals.

強(qiáng)調(diào)貓，討論的是哪種動物聰明可愛。

Cats are cute animals.

強(qiáng)調(diào)事實(shí)，討論的是貓是可愛的動物的事實(shí)。

Cats are cute animals.

強(qiáng)調(diào)可愛，討論的是貓是否可愛。

Chapter 1: The Praxis

"chapter 1"僅僅是個(gè)引用，后面strong里的內(nèi)容才是章節(jié)真正的名字。

Flowers, Bees, and Honey and other things I don"t understand

這里strong的使用是為了和其他內(nèi)容區(qū)分開來。

In this example, the strong element is used to denote the part of the text that the user is intended to read first.
在這個(gè)例子里，strong標(biāo)簽是用來指示用戶優(yōu)先查看的部分內(nèi)容。

Welcome to Remy, the reminder system.
Your tasks for today:

 
Turn off the oven.
 
Put out the trash.
 
Do the laundry.