blocks|key|278888|text|&lt;小于：<|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|278889|&gt;大于：>|278890|entityMap^0|0|4|7|1|0|0|4|7|1|0^^$0|@$1|2|3|4|5|6|7|J|8|@$9|K|A|L|B|C]|$9|M|A|N|B|C]]|D|@]|E|$]]|$1|F|3|G|5|6|7|O|8|@$9|P|A|Q|B|C]|$9|R|A|S|B|C]]|D|@]|E|$]]|$1|H|3|-4|5|6|7|T|8|@]|D|@]|E|$]]]|I|$]]

<code>&amp;lt;</code> Less than: <code>&lt;</code>

<code>&amp;gt;</code> Greater than: <code>&gt;</code>

blocks|key|2987860|text|它们用于显式定义小于和大于符号。如果你想输入<html>，而不想让它成为超文本标记语言中的一个标签，你可以使用它们。另一种方法是将<code>元素包装在代码周围，以避免遇到这种情况。|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|2987861|它们还可以用来表示数学运算符。|2987862|<!ENTITY+lt++++++CDATA+"&#60;"+++--+less-than+sign,+U%2B003C+ISOnum+-->
<!ENTITY+gt++++++CDATA+"&#62;"+++--+greater-than+sign,+U%2B003E+ISOnum+-->|code-block|syntax|javascript|2987863|http://www.w3.org/TR/html4/sgml/entities.html|2987864|entityMap|0|LINK|mutability|MUTABLE|url^0|M|6|1T|6|0|0|0|0|19|0|0^^$0|@$1|2|3|4|5|6|7|V|8|@$9|W|A|X|B|C]|$9|Y|A|Z|B|C]]|D|@]|E|$]]|$1|F|3|G|5|6|7|10|8|@]|D|@]|E|$]]|$1|H|3|I|5|J|7|11|8|@]|D|@]|E|$K|L]]|$1|M|3|N|5|6|7|12|8|@]|D|@$9|13|A|14|1|15]]|E|$]]|$1|O|3|-4|5|6|7|16|8|@]|D|@]|E|$]]]|P|$Q|$5|R|S|T|E|$U|N]]]]

They're used to explicitly define less than and greater than symbols. If one wanted to type out <code>&lt;html&gt;</code> and not have it be a tag in the HTML, one would use them. An alternate way is to wrap the <code>&lt;code&gt;</code> element around code to not run into that. 

They can also be used to present mathematical operators.

<pre><code>&lt;!ENTITY lt CDATA "&amp;#60;" -- less-than sign, U+003C ISOnum --&gt;
&lt;!ENTITY gt CDATA "&amp;#62;" -- greater-than sign, U+003E ISOnum --&gt;
</code></pre>

<a href="http://www.w3.org/TR/html4/sgml/entities.html" rel="noreferrer">http://www.w3.org/TR/html4/sgml/entities.html</a>

blocks|key|2987866|text|&lt;+==++lesser-than+==+<
&gt;+==+greater-than+==+>|type|code-block|depth|inlineStyleRanges|entityRanges|data|syntax|javascript|2987867|unstyled|entityMap^0|0^^$0|@$1|2|3|4|5|6|7|G|8|@]|9|@]|A|$B|C]]|$1|D|3|-4|5|E|7|H|8|@]|9|@]|A|$]]]|F|$]]

<pre><code>&amp;lt; == lesser-than == &lt;
&amp;gt; == greater-than == &gt;
</code></pre>

blocks|key|282762|text|其他人已经注意到了正确的答案，但没有清楚地解释最重要的原因：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|282763|282764|why我们需要这个吗？|unordered-list-item|offset|length|style|BOLD|282765|282766|<+and+>代表什么？|282767|282768|&lt;代表<标志。记住:+lt+==+less+than|CODE|282769|&gt;代表+>记住:+gt+==+greater+reater|282770|282771|为什么我们不能简单地在HTML中使用<和>字符呢？|282772|282773|这是因为>和<字符是超文本标记语言中的“保留”字符。|282774|超文本标记语言是一种标记语言：<和>用于表示不同元素的开始和结束:例如，<h1>和not用于显示大于或小于的符号。但是，如果您想要实际显示这些符号呢？您只需使用&lt;和&gt;，浏览器就会确切地知道如何显示它。|282775|282776|参考：https://dev.w3.org/html5/html-author/charref|282777|entityMap|0|LINK|mutability|MUTABLE|url|https://dev.w3.org/html5/html-author/charref^0|0|0|0|3|0|0|0|0|0|4|6|1|K|1|P|1|0|0|4|7|1|I|1|0|0|I|1|K|1|0|0|4|1|6|1|0|F|1|H|1|10|4|28|4|2D|4|0|0|3|18|0|0^^$0|@$1|2|3|4|5|6|7|1B|8|@]|9|@]|A|$]]|$1|B|3|-4|5|6|7|1C|8|@]|9|@]|A|$]]|$1|C|3|D|5|E|7|1D|8|@$F|1E|G|1F|H|I]]|9|@]|A|$]]|$1|J|3|-4|5|6|7|1G|8|@]|9|@]|A|$]]|$1|K|3|L|5|6|7|1H|8|@]|9|@]|A|$]]|$1|M|3|-4|5|6|7|1I|8|@]|9|@]|A|$]]|$1|N|3|O|5|E|7|1J|8|@$F|1K|G|1L|H|P]|$F|1M|G|1N|H|P]|$F|1O|G|1P|H|I]|$F|1Q|G|1R|H|I]]|9|@]|A|$]]|$1|Q|3|R|5|E|7|1S|8|@$F|1T|G|1U|H|P]|$F|1V|G|1W|H|P]|$F|1X|G|1Y|H|I]]|9|@]|A|$]]|$1|S|3|-4|5|6|7|1Z|8|@]|9|@]|A|$]]|$1|T|3|U|5|6|7|20|8|@$F|21|G|22|H|P]|$F|23|G|24|H|P]]|9|@]|A|$]]|$1|V|3|-4|5|6|7|25|8|@]|9|@]|A|$]]|$1|W|3|X|5|E|7|26|8|@$F|27|G|28|H|P]|$F|29|G|2A|H|P]]|9|@]|A|$]]|$1|Y|3|Z|5|E|7|2B|8|@$F|2C|G|2D|H|P]|$F|2E|G|2F|H|P]|$F|2G|G|2H|H|P]|$F|2I|G|2J|H|P]|$F|2K|G|2L|H|P]]|9|@]|A|$]]|$1|10|3|-4|5|6|7|2M|8|@]|9|@]|A|$]]|$1|11|3|12|5|6|7|2N|8|@]|9|@$F|2O|G|2P|1|2Q]]|A|$]]|$1|13|3|-4|5|6|7|2R|8|@]|9|@]|A|$]]]|14|$15|$5|16|17|18|A|$19|1A]]]]

Others have noted the correct answer, but have not clearly explained the all-important reason:
<ul>
<li>why do we need this?</li>
</ul>
<h3 id="what-do-and-stand-for-080k">What do &lt; and &gt; stand for?</h3>
<ul>
<li><code>&amp;lt;</code> stands for the <code>&lt; </code> sign. Just remember: lt == less than</li>
<li><code>&amp;gt;</code> stands for the <code>&gt;</code> Just remember: gt == greater than</li>
</ul>
<h3 id="why-cant-we-simply-use-the-and-characters-in-html-zn94">Why can’t we simply use the <code>&lt;</code> and <code>&gt;</code> characters in HTML?</h3>
<ul>
<li>This is because the <code>&gt;</code> and <code>&lt;</code> characters are ‘reserved’ characters in HTML.</li>
<li>HTML is a mark up language: The <code>&lt;</code> and <code>&gt;</code> are used to denote the starting and ending of different elements: e.g. <code>&lt;h1&gt;</code> and not for the displaying of the greater than or less than symbols. But what if you wanted to actually display those symbols? You would simply use <code>&amp;lt;</code> and <code>&amp;gt;</code> and the browser will know exactly how to display it.</li>
</ul>
Reference: <a href="https://dev.w3.org/html5/html-author/charref" rel="nofollow noreferrer">https://dev.w3.org/html5/html-author/charref</a>

blocks|key|282741|text|&lt+=小于<，&gt+=大于>|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|282742|entityMap^0|0|3|7|1|9|3|G|1|0^^$0|@$1|2|3|4|5|6|7|H|8|@$9|I|A|J|B|C]|$9|K|A|L|B|C]|$9|M|A|N|B|C]|$9|O|A|P|B|C]]|D|@]|E|$]]|$1|F|3|-4|5|6|7|Q|8|@]|D|@]|E|$]]]|G|$]]

<code>&amp;lt</code> = less than <code>&lt;</code>, <code>&amp;gt</code> = greater than <code>&gt;</code>

blocks|key|277143|text|&gt;+and+&lt;是超文本标记语言中>和<字符的字符实体引用。|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|277144|不能在文件中使用小于号(<)或大于号(>)，因为浏览器会将它们与标签混合在一起。|277145|对于这些困难，您可以使用实体名称(&gt;)和实体编号(&#60;)。|277146|entityMap^0|0|D|M|1|O|1|0|0|H|4|S|5|0^^$0|@$1|2|3|4|5|6|7|L|8|@$9|M|A|N|B|C]|$9|O|A|P|B|C]|$9|Q|A|R|B|C]]|D|@]|E|$]]|$1|F|3|G|5|6|7|S|8|@]|D|@]|E|$]]|$1|H|3|I|5|6|7|T|8|@$9|U|A|V|B|C]|$9|W|A|X|B|C]]|D|@]|E|$]]|$1|J|3|-4|5|6|7|Y|8|@]|D|@]|E|$]]]|K|$]]

<code>&amp;gt; and &amp;lt;</code> is a character entity reference for the <code>&gt;</code> and <code>&lt;</code> character in HTML.

It is not possible to use the less than (&lt;) or greater than (>) signs in your file, because the browser will mix them with tags.

for these difficulties you can use entity names(<code>&amp;gt;</code>) and entity numbers(<code>&amp;#60;</code>).

blocks|key|278906|text|&lt;代表lesser+than+(<)+symbol，&gt;符号代表greater+than+(>)+symbol。|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|278907|有关HTML实体的详细信息，请访问此链接：|278908|https://www.w3schools.com/HTML/html_entities.asp|278909|entityMap|0|LINK|mutability|MUTABLE|url^0|0|4|6|M|T|4|11|N|0|0|0|1C|0|0^^$0|@$1|2|3|4|5|6|7|Q|8|@$9|R|A|S|B|C]|$9|T|A|U|B|C]|$9|V|A|W|B|C]|$9|X|A|Y|B|C]]|D|@]|E|$]]|$1|F|3|G|5|6|7|Z|8|@]|D|@]|E|$]]|$1|H|3|I|5|6|7|10|8|@]|D|@$9|11|A|12|1|13]]|E|$]]|$1|J|3|-4|5|6|7|14|8|@]|D|@]|E|$]]]|K|$L|$5|M|N|O|E|$P|I]]]]

<code>&amp;lt;</code> stands for <code>lesser than (&lt;) symbol</code> and, the <code>&amp;gt;</code> sign stands for <code>greater than (&gt;) symbol</code>.

For more information on HTML Entities, visit this link: 

<a href="https://www.w3schools.com/HTML/html_entities.asp" rel="nofollow noreferrer">https://www.w3schools.com/HTML/html_entities.asp</a>

blocks|key|282779|text|在HTML中，小于号用在标记的开头。如果你在内容中使用这个方括号"<test1>“，你的方括号内容将是不可见的，html渲染器假设它是一个html标签，用它的ASCI号改变字符可以防止这个问题。|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|282780|使用html友好名称：|282781|++&lt;test1&gt;+|code-block|syntax|javascript|282782|或使用asci编号：|282783|+&#60;test1&#62;|282784|或复杂的asci：|282785|&#60;&#116;&#101;&#115;&#116;&#49;&#62;|282786|结果：|282787|asci参考：https://www.w3schools.com/charsets/ref_html_ascii.asp|282788|entityMap|0|LINK|mutability|MUTABLE|url|https://www.w3schools.com/charsets/ref_html_ascii.asp^0|X|7|0|0|0|0|0|0|0|0|7|1H|0|0^^$0|@$1|2|3|4|5|6|7|16|8|@$9|17|A|18|B|C]]|D|@]|E|$]]|$1|F|3|G|5|6|7|19|8|@]|D|@]|E|$]]|$1|H|3|I|5|J|7|1A|8|@]|D|@]|E|$K|L]]|$1|M|3|N|5|6|7|1B|8|@]|D|@]|E|$]]|$1|O|3|P|5|J|7|1C|8|@]|D|@]|E|$K|L]]|$1|Q|3|R|5|6|7|1D|8|@]|D|@]|E|$]]|$1|S|3|T|5|J|7|1E|8|@]|D|@]|E|$K|L]]|$1|U|3|V|5|6|7|1F|8|@]|D|@]|E|$]]|$1|W|3|X|5|6|7|1G|8|@]|D|@$9|1H|A|1I|1|1J]]|E|$]]|$1|Y|3|-4|5|6|7|1K|8|@]|D|@]|E|$]]]|Z|$10|$5|11|12|13|E|$14|15]]]]

In HTML, the less-than sign is used at the beginning of tags. 
if you use this bracket "<code>&lt;test1&gt;</code>" in content, your bracket content will be unvisible, html renderer is assuming it as a html tag, changing chars with it's ASCI numbers prevents the issue.

with html friendly name:

<pre><code> &amp;lt;test1&amp;gt; 
</code></pre>

or with asci number:

<pre><code> &amp;#60;test1&amp;#62;
</code></pre>

or comple asci:

<pre><code>&amp;#60;&amp;#116;&amp;#101;&amp;#115;&amp;#116;&amp;#49;&amp;#62;
</code></pre>

result: &#60;&#116;&#101;&#115;&#116;&#49;&#62;

asci referance: <a href="https://www.w3schools.com/charsets/ref_html_ascii.asp" rel="noreferrer">https://www.w3schools.com/charsets/ref_html_ascii.asp</a>

blocks|key|3201400|text|在rails中|type|unstyled|depth|inlineStyleRanges|entityRanges|offset|length|data|3201401|&lt=++++this+is++++<=
=&gt++++this+is++++=>|code-block|syntax|javascript|3201402|entityMap|0|LINK|mutability|MUTABLE|url|/questions/tagged/rails^0|1|5|0|0|0^^$0|@$1|2|3|4|5|6|7|Q|8|@]|9|@$A|R|B|S|1|T]]|C|$]]|$1|D|3|E|5|F|7|U|8|@]|9|@]|C|$G|H]]|$1|I|3|-4|5|6|7|V|8|@]|9|@]|C|$]]]|J|$K|$5|L|M|N|C|$O|P]]]]

in <a href="/questions/tagged/rails" class="post-tag" title="show questions tagged 'rails'" rel="tag">rails</a>:

<pre><code>&amp;lt= this is &lt;=
=&amp;gt this is =&gt;
</code></pre>

I know that the entities <code>&amp;lt;</code> and <code>&amp;gt;</code> are used for <code>&lt;</code> and <code>&gt;</code>, but I am curious what these names stand for.

Does <code>&amp;lt;</code> stand for something like "Left tag" or is it just a code?

What do &lt; and &gt; stand for?

我知道实体&lt;和&gt;用于<和>，但我很好奇这些名称代表什么。&lt;代表的是"Left tag“之类的东西吗?还是它只是一个代码？

问和&gt；代表什么？
EN

回答 9

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问和&gt；代表什么？EN

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问和&gt；代表什么？
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