HTML與XHTML的主要區(qū)別在於語法嚴(yán)格性、文件類型處理和錯誤處理方式。 HTML更靈活，允許標(biāo)籤大小寫混合、標(biāo)籤可不閉合、屬性值無需引號；而XHTML遵循XML規(guī)則，要求所有標(biāo)籤小寫、必須閉合、屬性值需加引號。 HTML文件通常以text/html MIME類型傳輸，使用HTML解析器解析；XHTML應(yīng)以application/xhtml xml類型傳輸，否則可能導(dǎo)致解析錯誤。 HTML對錯誤寬容，瀏覽器會盡力渲染；XHTML則因語法錯誤會停止渲染並報錯。雖然XHTML曾被視為未來方向，但如今HTML5已成為主流，它融合了HTML與XHTML的優(yōu)點，同時避免強(qiáng)制嚴(yán)格的XML語法，更適合通用網(wǎng)頁開發(fā)。

HTML and XHTML are both markup languages used for structuring web content, but they have distinct rules and purposes that affect how developers write and maintain code. The main difference lies in their syntax and parsing requirements — HTML is more forgiving, while XHTML is stricter and follows XML rul??es.

Syntax Strictness

One of the most noticeable differences is how strict each format is about syntax.

<li> HTML allows for more flexibility. Tags can be written in uppercase or lowercase, some tags can be left unclosed (like <li> or <p></p> ), and attribute values don't always need quotes. <li> XHTML , on the other hand, requires well-formed documents. All tags must be lowercase, every opened tag must be closed properly (eg, <br> instead of <br> ), and all attributes must have quotes around their values.

This strictness makes XHTML documents easier to process with XML tools but also adds more overhead when writing or maintaining code manually.

File Type and MIME Handling

Another key distinction is how browsers handle files based on their type.

<li> HTML files are usually served with the text/html MIME type, which means browsers will parse them using an HTML parser. <li> XHTML should be served as application/xhtml xml . If you serve XHTML with the HTML MIME type, older browsers might not interpret it correctly, leading to rendering issues or broken pages.

In practice, this means that if you're using XHTML, your server configuration needs to support the correct MIME type — something many developers prefer to avoid due to compatibility concerns.

Error Handling

How errors are handled is another practical difference that affects debugging.

<li> In HTML , browsers tend to be lenient. Even if your markup has errors, browsers often try to render the page anyway. This can hide problems and make debugging trickier. <li> With XHTML , any syntax error usually causes the browser to stop rendering and display an error message. While this can be frustrating during development, it helps catch issues early and ensures cleaner code overall.

Tooling and Usage Today

While XHTML was once promoted as the future of web markup, its adoption never fully took off.

<li> Most modern websites use HTML5 , which blends the best parts of HTML and XHTML without enforcing XML's strict syntax. <li> XHTML is still relevant in specific environments like embedded systems or applications that require XML processing, but for general web development, it's largely been replaced by HTML5 with stricter coding practices encouraged through linters and validators.

So unless you're working in a context that specifically needs XML parsing, sticking with HTML5 and writing clean, semantic markup is usually the better choice.

基本上就這些。

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