- Blockquote translates this sentence into English, output only plain text, do not output any other content.

The `blockquote` tag in HTML is used to mark block-level quoted content, typically displayed with indentation. It supports the `cite` attribute to indicate the source of the quote. Unlike the inline `q` tag, it is a block-level element and can be customized with CSS, such as adding backgrounds, borders, or quotation marks. It is commonly used in scenarios like blog comments, famous quotes, etc., and offers SEO and accessibility advantages. When using it, ensure proper source attribution and avoid misuse solely for styling effects. When nesting, maintain content clarity, and adapt styles for different devices and language environments. Mainstream CSS frameworks provide preset styles, and it is widely supported in content management systems. Proper use of `blockquote` enhances content structure and semantics.

<pre>-Preformatted text

The `<pre>` tag in HTML is used to define preformatted text, preserving original spaces, line breaks, and formatting. It is commonly used to display code blocks or content requiring maintained formatting. Text inside the `<pre>` tag is displayed in a monospace font, retaining all spaces and line breaks. Common use cases include displaying code blocks (often combined with the `<code>` tag for enhanced semantics), ASCII art, or tables. CSS can be used to adjust `<pre>` tag styles, such as background color, margins, and overflow control. Special characters must be escaped to avoid being parsed as HTML tags. When dynamically inserting content, it is recommended to use `textContent` instead of `innerHTML`. Advanced usage includes integrating syntax highlighting libraries like Prism.js or Highlight.js, as well as optimizing responsive design for mobile displays. The `<pre>` tag differs from `<code>` and `<textarea>` tags—the former is for displaying formatted text, while the latter are for inline code and editable multi-line text, respectively. Practical applications include displaying JSON data and command-line output.

<hr> - Horizontal divider line

The `<hr>` tag in HTML is used to create a horizontal divider, primarily serving the function of visually separating content sections. Its basic usage involves inserting it directly into HTML without requiring a closing tag. Browsers typically render it as a 1px gray line with a shadow effect. In modern development, it is recommended to use CSS instead of traditional attributes, as CSS enables various styling effects such as gradients, dashed lines, and custom patterns. The `<hr>` tag carries semantic meaning and can be enhanced for accessibility using ARIA. In responsive design, it can be combined with media queries to achieve adaptive effects. It can also be utilized for creative designs, such as decorative section dividers or animated separators. Browser compatibility issues should be noted, and in specific scenarios, alternatives like `<div>` may be considered. Popular CSS frameworks like Bootstrap and Tailwind provide preset styles for it.

- Line break translates this sentence into English, output plain text directly, do not output other content

The `<br>` tag in HTML is an empty element used for line breaks in text and does not require closing. It forces a line break at a specified position without creating paragraph spacing. Unlike the `<p>` tag, `<br>` only performs a line break and has no semantic meaning or additional spacing. It is commonly used in addresses, poems, and other scenarios requiring precise line control. When using it, avoid excessive `<br>` tags and prioritize CSS for spacing. All browsers fully support the `<br>` tag, which has specific uses in responsive design and template engines. Modern development discourages the deprecated `clear` attribute. Rich text editors handle `<br>` tags differently. The `<br>` tag has remained simple and efficient for line breaks since HTML 2.0.

- Paragraph text translates this sentence into English, outputting only plain text directly without any additional content.

The `<p>` tag in HTML is a fundamental container for defining paragraphs. Browsers automatically add spacing before and after paragraphs to create visual separation. It uses a double-tag structure, supports global attributes, but no longer supports the `align` attribute. Its default styling includes top and bottom margins, which can be reset via CSS. The `<p>` tag can only contain phrasing content and cannot nest block-level elements or itself. Usage requires attention to whitespace handling and auto-closing behavior. For accessibility, it defaults to a paragraph role and can be enhanced with ARIA attributes. Performance-wise, avoid deep nesting and distinguish it properly from tags like `<br>`, `<pre>`, etc. Historically, HTML5 restored lenient syntax but explicit closing is still recommended. JavaScript can dynamically manipulate paragraph content. Server-side rendering requires content escaping. Testing should consider edge cases and style debugging. For internationalization, handle text direction and mixed languages. Print styles can optimize pagination.

`<h1>` to `<h6>` - heading levels

HTML heading tags h1 to h6 are used to build the hierarchical structure of a webpage. h1 serves as the main title and should be unique per page, while h2 to h6 represent subheadings in descending order, forming a clear document outline. Proper use of headings is crucial for SEO and accessibility—avoid skipping levels or using multiple h1 tags. In contexts like news or e-commerce, maintain a semantic structure. CSS can customize heading styles but should not alter the HTML hierarchy. For dynamically generated content, preserve heading relationships. ARIA attributes can enhance semantics for complex components. Responsive design should adjust headings via CSS rather than modifying HTML structure. In internationalization scenarios, consider language direction. Heading content should be concise and include key information. Combining headings with microdata can boost SEO. Print styles must ensure headings remain clear. Interactive features can enhance headings via JavaScript. Heading text should be brief and avoid redundancy.

The `<base>` tag sets the base URL.

The HTML `<base>` tag is used to set the base URL and default opening behavior for all relative URLs on a page. It includes two main attributes: `href` and `target`. The `href` specifies the base URL, against which all relative paths are resolved, while `target` defines the default opening behavior for links. This tag is commonly used for CDN resource management, multi-environment deployment, and single-page application routing. When using it, pay attention to priority and placement, and avoid multiple `<base>` tags. Browser compatibility is excellent, with all modern browsers supporting it. In practical development, root-relative paths or template variables can serve as alternatives. Server configurations may affect its behavior, so consider performance and security implications, particularly guarding against open redirect risks. For debugging, inspect `document.baseURI` or use developer tools.

`<script>` - client-side script translates this sentence into English, output only plain text, do not output any other content

The `<script>` tag in HTML is used to embed or reference JavaScript code, supporting both inline scripts and external scripts via the `src` attribute. It includes various attributes like `async`, `defer`, `type`, `src`, `crossorigin`, and `integrity` to control script loading and execution order. By default, scripts block document parsing. The `async` attribute enables asynchronous loading without blocking parsing, executing immediately after download, while `defer` delays execution until the document is fully parsed. Inline scripts are written directly in HTML, whereas external scripts are stored separately for easier maintenance and caching. Scripts can also be loaded dynamically via JavaScript. Modern JavaScript supports modularization using the `type="module"` attribute. Script loading impacts page performance, so it's important to optimize placement and use of `async` and `defer`, merge files, implement code splitting, and lazy loading. Security risks like XSS attacks should be mitigated using Content Security Policy (CSP) to restrict sources and validate integrity. Browser implementations vary, requiring compatibility considerations. Modern frontend frameworks like React and Vue have their own handling methods. Debugging can be done using developer tools, breakpoints, and the Network panel. Common issues include scripts not loading, undefined variables, and cross-origin problems. Advanced techniques include JSONP, Web Workers, and Service Workers. Performance monitoring can leverage the Performance API. Best practices include minimizing inline scripts, code minification and obfuscation, using modern features with graceful degradation, ensuring accessibility, and considering progressive enhancement.

`<style>-embedded CSS styles translate this sentence into English`

The `<style>` tag in HTML is used to define CSS styles directly within the document, making it suitable for small projects or rapid development but less ideal for maintaining large-scale projects. It is typically placed in the `<head>` section and supports attributes like `media` for responsive design. Inline styles (defined within the `<style>` tag) have higher priority than external stylesheets but lower than inline styles (defined using the `style` attribute). The `<style>` tag can be combined with media queries and CSS variables, and its content can be dynamically modified using JavaScript. In Web Components, it can be used for Shadow DOM style encapsulation. While convenient, large projects are advised to use external stylesheets. The `<style>` tag is fully supported in all modern browsers. When using it, keep styles concise, add comments, avoid overly specific selectors, and consider methodologies like BEM for organizing styles. Under CSP (Content Security Policy), special handling may be required. Its support is limited in HTML emails, and it can also be used to design print-specific styles.

`<link>` - External resource link

The `<link>` tag in HTML is used to define the relationship between a document and external resources, primarily located in the `<head>` section. Common uses include linking external stylesheets, website icons (favicons), preloading resources, and more. The basic syntax includes `rel` to define the relationship, `href` to specify the URL, and `type` (optional) to indicate the MIME type. Advanced usage involves media queries, specification versions, RSS feeds, PWA manifest files, cross-origin resource handling, and performance optimization techniques like DNS prefetching, preconnecting, and prefetching. Browser compatibility requires attention, as IE11 and earlier versions have limited support. Practical examples demonstrate complete header links and dynamic stylesheet loading. Security considerations emphasize using trusted sources and validating resource integrity. Debugging techniques include checking the Network panel, verifying attributes, and auditing with Lighthouse.