The role and usage scenarios of the '<progress>' tag

The HTML5 `<progress>` tag is used to display task progress, such as file uploads/downloads or form completion. It sets the current value and maximum value via the `value` and `max` attributes, showing an indeterminate state when `value` is unset. This tag supports CSS styling customization and can be dynamically updated with JavaScript. Unlike the `<meter>` tag, `<progress>` is specifically designed for dynamic tasks. Accessibility and browser compatibility should be considered. Complex calculation progress can be handled using Web Workers, while mobile devices require attention to touch areas and landscape adaptation. Performance optimization includes minimizing repaints and using `requestAnimationFrame`. Testing should validate edge cases and attribute changes.

The role and usage scenarios of the '<mark>' tag

The HTML5 `<mark>` tag is used to highlight specific parts of text, visually appearing with a yellow background by default. Its primary function is to emphasize text fragments, with semantics leaning more toward relevance rather than importance. Typical use cases include highlighting search keywords, providing user action feedback, and marking key content in educational annotation systems. While the default styling is yellow background with black text, it can be fully customized via CSS. Compared to other tags like `<strong>` and `<em>`, `<mark>` is more suitable for search matches and dynamic highlighting. When combined with JavaScript, it enables real-time highlighting effects. Accessibility considerations such as ARIA attribute supplementation and color contrast should also be noted. In terms of browser compatibility, all modern browsers support the `<mark>` tag, though special handling may be required for printing. In advanced applications, it can also be used for code syntax highlighting, achieving simple keyword marking effects through CSS.

The role and usage scenarios of the '<time>' tag

The HTML5 `<time>` tag is a semantic element used to mark dates, times, or time ranges. It provides a machine-readable, standardized time format via the `datetime` attribute while displaying human-readable content within the tag. This tag enhances code readability and helps search engines and assistive technologies understand time-related information. Typical use cases include blog post publication dates, event schedules, and historical timelines. Advanced applications involve timezone handling, duration representation, and dynamic interaction with JavaScript. The article also covers styling customization, combining with other HTML elements, browser compatibility considerations, and enhancing SEO by integrating microformats and structured data. Finally, it offers best practice recommendations for real-world projects, such as CMS integration and internationalization handling.

The usage of '<figure>' and '<figcaption>' tags

In HTML5, the `<figure>` and `<figcaption>` tags are specifically designed for handling media content and their captions in documents. The `<figure>` tag serves as a semantic container that can include various types of content such as images, code, charts, and more. The `<figcaption>` provides a title or description for it. While the two tags are often used together, it is not mandatory. The `<figcaption>` can be flexibly positioned and styled using CSS. These tags support complex content combinations, such as displaying multiple images or data visualizations. When using them, accessibility should be considered to ensure the `alt` attribute and captions do not duplicate information. They can be combined with responsive design to create layouts that adapt to different devices. Additionally, they can work with the `<picture>` element to achieve responsive images. In technical documentation, these tags can be used to present code examples or table data. With JavaScript, dynamic content updates can also be implemented.

The role and usage scenarios of the '<footer>' tag

The `<footer>` tag in HTML5 is a semantic element used to define the footer content of a document or section. It enhances code readability and helps search engines and assistive technologies understand the page structure. The `<footer>` tag can appear at any level of the page and is not restricted to the very bottom. Typical use cases include serving as a container for the entire webpage's footer, containing copyright notices, legal information, contact details, etc. When used inside `<article>` or `<section>`, it can provide metadata related to the current content. When paired with `<blockquote>`, it can be used to cite the source of a quotation. Technically, it’s important to follow nesting rules—it cannot be a child of `<header>`, `<footer>`, or `<address>`. CSS can be used to create various styles of footer layouts. To improve accessibility, ARIA attributes can be added. In practical applications, e-commerce website footers often contain multi-level content, while blog post footers may include interactive elements. Mobile devices require special handling, such as responsive adjustments. Proper use of `<footer>` offers multiple benefits, including search engine optimization, code maintainability, and accessibility. Modern websites often dynamically load footer content using JavaScript, and multilingual websites require special treatment for their footers.

Core knowledge points of HTML

Basic concepts of HTML include defining the document structure, tags, elements, and the difference between attributes. It covers the document type declaration, comment syntax, handling whitespace and line breaks, and representing special characters. Encoding settings, text formatting tags, headings, paragraphs, line breaks, horizontal rules, emphasis, superscripts and subscripts, preformatted text, quotations, addresses, abbreviations, code, keyboard input, and variable tags are included. Hyperlinks and anchors involve basic syntax, external and local links, mailto and download links, in-page anchors, the `target` attribute, `title` attribute, link states, and styling. The section on images and multimedia explains image tags, alternative text, width and height, alignment, borders, backgrounds, audio, video, and Flash embedding. Tables introduce basic structure, border settings, width and height, cell spacing and padding, captions, header cells, cell merging, column grouping, and nesting. Forms cover input controls, basic structure, submission methods, target windows, various input fields, buttons, file uploads, hidden fields, multi-line text, dropdown selections, fieldsets, and lists (unordered, ordered, and definition lists), including style control and nesting for navigation. Frames and windows explain frameset concepts, splitting methods, defining individual frames, the `name` attribute, scrollbar and border control, nesting, inline frames, and their communication advantages and disadvantages. Meta information and head content discuss the role of `head`, the importance of `title`, common `meta` usage (keywords, descriptions, refresh/redirects, base URLs), linking external resources (stylesheets, scripts), and character set declarations. HTML document structure and semantics explore the differences between `div` and `span`, the use of `id` and `class`, semantic meaning, content sections, text direction, language attributes, document outlines, accessibility, browser compatibility, and validation methods.

Build a static webpage using HTML5

HTML5 is the fifth major revision of HyperText Markup Language, serving as the standard language for building web content. Compared to the previous HTML4 and XHTML standards, HTML5 simplifies the document type declaration and introduces many new features, such as semantic tags, multimedia support, and local storage, enabling developers to create richer and more interactive web applications. Key features include semantic tags like `<header>`, `<nav>`, `<section>`, `<article>`, `<aside>`, and `<footer>`; multimedia support via `<video>` and `<audio>` tags; enhanced forms with new input types; Canvas for drawing; local storage (`localStorage` and `sessionStorage`); geolocation; Web Workers for background threads; and drag-and-drop APIs. Combined with CSS3, these features enable responsive design, allowing web pages to adapt to different device screen sizes. Additionally, HTML5 offers performance optimization solutions, such as resource compression and image optimization.

The combination of HTML5 and the Internet of Things (IoT)

The integration of HTML5 and the Internet of Things (IoT) is transforming human-computer interaction by leveraging technologies like WebSocket, Canvas, and WebRTC to enable cross-platform real-time data visualization and remote control. WebSocket provides efficient bidirectional communication, replacing traditional HTTP polling. Canvas dynamically renders sensor data to create real-time dashboards. WebComponents encapsulate reusable device controls, while geolocation enables location-based automation. IndexedDB stores device historical data, and ServiceWorker ensures offline access. The Web Cryptography API secures instruction transmission, and WebAuthn adds biometric authentication. WebBluetooth and WebUSB facilitate direct device connections. Together, these technologies build an HTML5-based IoT solution.

HTML5 and hybrid development (Cordova, Electron, etc.)

HTML5, as a core technology in modern web development, enables cross-platform application construction through hybrid development frameworks. Cordova packages HTML5 apps into native application wrappers, supporting platforms like iOS and Android, and accesses device features via plugins. Electron combines Chromium and Node.js to develop desktop applications, supporting a main process and renderer process architecture. Hybrid development requires attention to performance optimization, such as WebView performance bottlenecks and memory management, as well as security practices like Cordova security configurations and Electron security settings. Practical cases demonstrate code-sharing solutions and system integration. Modern alternatives include Capacitor and Tauri. Debugging and testing methods cover remote debugging and automated testing. Build and deployment involve multi-platform configuration and packaging optimization. Future technological advancements include WebAssembly integration and progressive web application convergence.

HTML5 and backend technologies (Node.js, RESTful API, etc.)

HTML5, as a core technology in modern web development, not only provides rich front-end functionalities but also tightly integrates with back-end technologies like Node.js and RESTful APIs to build a comprehensive full-stack development ecosystem. The article delves into how HTML5 interacts with back-end systems through the Fetch API and WebSocket, as well as the advantages of Node.js as a back-end technology, including its event-driven model and modular architecture. It also covers RESTful API design practices, real-time data applications using WebSocket technology, performance optimization, security considerations, modern full-stack development patterns like GraphQL, deployment strategies, continuous integration, and emerging technologies such as WebAssembly and edge computing. This showcases the diverse application scenarios and future trends of combining HTML5 with back-end technologies.