What is the role of semantic HTML in web accessibility?

Semantic HTML plays a crucial role in web accessibility by providing meaningful structure and context to web content, which is essential for users who rely on assistive technologies like screen readers. Here's how semantic HTML contributes to web accessibility:

1. **Clear Document Structure:** Semantic HTML elements such as `<header>`, `<nav>`, `<main>`, `<section>`, `<article>`, and `<footer>` provide a clear and hierarchical structure to web documents. This structure helps assistive technologies understand the organization of content and navigate through it more efficiently.

2. **Navigational Aids:** Semantic HTML elements like `<nav>`, `<ul>`, `<ol>`, and `<li>` help define navigation menus and lists, making it easier for users to locate and navigate to different sections or pages of a website.

3. **Headings and Landmarks:** Proper use of heading elements (`<h1>` to `<h6>`) allows users to quickly grasp the main topics and sections of a webpage. Screen readers use headings to create an outline of the content, enabling users to navigate directly to specific sections of interest. Additionally, landmark roles (e.g., `<header>`, `<main>`, `<footer>`, `<nav>`, `<aside>`) help users understand the overall structure of a page and navigate to important sections more efficiently.

4. **Form Accessibility:** Semantic HTML elements like `<form>`, `<input>`, `<label>`, `<select>`, `<textarea>`, and `<button>` provide the necessary structure and labels for creating accessible forms. Screen readers use these elements to announce form controls and guide users through the form-filling process, ensuring that users can interact with forms effectively.

5. **Alternative Text for Images:** The `alt` attribute in `<img>` elements allows authors to provide alternative text descriptions for images. Screen readers use this alternative text to convey the content and purpose of images to users who cannot see them, including users with visual impairments.

6. **Interactive Elements:** Semantic HTML elements like `<button>`, `<a>`, and `<input type="button">` provide accessible alternatives for creating interactive elements such as buttons and links. Screen readers recognize these elements and convey their purpose and functionality to users, enabling users to interact with them using keyboard navigation or other assistive technologies.

In summary, semantic HTML enhances web accessibility by providing a well-structured, navigable, and understandable framework for web content. By using semantic HTML elements appropriately, web developers can ensure that their websites are accessible to all users, including those with disabilities who rely on assistive technologies to access the web.