<p>HTML標籤用於定義網頁內容的結構和語義，通常成對出現，如</p> <p>This is a paragraph.</p>，部分標籤如或<br>為自閉合標籤；常見標籤包括<h1>至<h6>表示標題、<div>用於分組、<a>定義鏈接、<ul>、 <ol>、<li>用於列表。 HTML屬性提供額外信息，以name-value形式出現在標籤內，如href="https://example.com"指定鏈接地址，src指定圖片路徑，alt增強可訪問性和SEO，class和id用於CSS樣式與唯一標識，data-*屬性支持JavaScript交互組件；屬性需依附於對應標籤使用，如href僅適用於<a>、src主要用於等，部分屬性如required無需賦值。標籤與屬性協作構建功能完整、結構清晰、語義明確的網頁。 <p></p> <p> HTML tags and attributes are the building blocks of any webpage. Tags define the structure and meaning (semantics) of content, while attributes provide extra information about those tags. </p>

What Are HTML Tags?

<p> HTML tags are like labels that tell the browser how to display content. They're enclosed in angle brackets and usually come in pairs: an opening tag and a closing tag. The content goes between them. </p> <p> For example:</p>

 <p>This is a paragraph.</p>

<p> Here, <p> is the opening tag, </p> is the closing tag, and everything in between is the content. Browsers know to display this as a paragraph. </p><p> Some tags are self-closing, like <img src="/static/imghw/default1.png" data-src="photo.jpg" class="lazy" alt="HTML標籤和屬性解釋了什麼？" > or <br> , which don't need a separate closing tag.</p><p> Common tags include:</p><ul><li> <h1> to <h6> for headings<li> <div> for grouping sections<li> <a> for links<li> <ul> , <ol> , and <li> for lists<p> Tags help structure your page so both browsers and assistive technologies (like screen readers) can understand it.</p>

What Are HTML Attributes?

<p> Attributes give more details about an HTML element. They appear inside the opening tag and usually come in name-value pairs.</p><p> For example:</p>

 <a href="https://example.com">Click here</a>

<p> In this case, href is the attribute name, and "https://example.com" is its value. It tells the browser where the link should go.</p><p> Some common attributes you'll see:</p><ul><li> class – used for styling with CSS<li> id – gives a unique identifier to an element<li> src – used in images to specify the file path<li> alt – provides alternative text for images<p> You can also use custom data attributes like data-role="menu" when building interactive components with JavaScript.</p>

How Tags and Attributes Work Together

<p> Tags set the role of an element, and attributes fine-tune how that element behaves or looks. For instance:</p>

 <img src="/static/imghw/default1.png"  data-src="photo.jpg"  class="lazy" alt="A description of the image">

<p> In this example:</p><ul><li> <img alt="HTML標籤和屬性解釋了什麼？" > is the tag — it tells the browser to show an image<li> src tells it which image to load<li> alt describes what the image shows, which helps accessibility and SEO<p> Another example:</p>

 <input type="text" placeholder="Enter your name" required>

<p> Here, the type attribute defines what kind of input it is, placeholder gives a hint to users, and required makes sure they fill it out before submitting a form.</p> <p> You'll often see multiple attributes on one tag, especially in forms or interactive elements.</p>

When to Use Which Attribute

<p> Not every attribute works on every tag. Some are specific to certain elements. For example:</p> <ul> <li> href only works with <a> , <link> , and a few others <li> src is used mainly with <img alt="HTML標籤和屬性解釋了什麼？" > , <script></script> , and <iframe></iframe> <li> type appears on <input> , <button></button> , and <script></script> <p> It's good practice to look up which attributes are valid for each tag. You can check on sites like MDN Web Docs or W3Schools.</p> <p> Also, some attributes don't need values — like required in forms. Just having them there means "yes, turn this on."</p>

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<p> That's the basic idea. You don't need to memorize all of them — just get comfortable with the most common ones. As you build more pages, it'll become second nature.</p>