| Introduction to HTML |
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| Introduction to HTML |
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| HTML Attributes |
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| HTML5 Semantic Elements |
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| HTML Graphics |
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HTML (HyperText Markup Language) and XHTML (Extensible HyperText Markup Language) are both markup languages used for creating web pages. While they are similar in many ways, there are key differences between them. Let’s delve into the details and see some examples to illustrate the differences.
HTML (HyperText Markup Language)
HTML is the standard markup language used to create web pages. It was developed in the early 1990s and has evolved over time. HTML is designed to be forgiving in terms of syntax and structure, which means that browsers will often try to display HTML documents even if they contain errors.
Key Characteristics of HTML:
- Syntax Flexibility: HTML is forgiving of minor errors in the code.
- Case Insensitivity: Tags and attributes in HTML are not case-sensitive.
- Optional Closing Tags: Some tags (e.g.,
<li>,<p>,<td>) do not require closing tags. - Attribute Values: Attribute values can be unquoted if they don’t contain spaces or special characters.
Example of HTML:
<!DOCTYPE html>
<html>
<head>
<title>HTML Example</title>
</head>
<body>
<h1>Welcome to HTML</h1>
<p>This is a paragraph in HTML.</p>
<img decoding="async" src="image.jpg" alt="Image">
</body>
</html>
XHTML (Extensible HyperText Markup Language)
XHTML is a reformulation of HTML as an application of XML (Extensible Markup Language). It was developed to bring the rigor of XML to HTML, ensuring a stricter syntax and better compatibility with XML tools.
Key Characteristics of XHTML:
- Strict Syntax: XHTML requires documents to be well-formed.
- Case Sensitivity: Tags and attributes in XHTML are case-sensitive and must be written in lower case.
- Mandatory Closing Tags: All elements must be properly closed, including empty elements like
<br />. - Attribute Values: Attribute values must always be quoted.
- Document Structure: XHTML documents must be properly nested and follow XML rules.
Example of XHTML:
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd">
<html xmlns="http://www.w3.org/1999/xhtml" xml:lang="en" lang="en">
<head>
<title>XHTML Example</title>
</head>
<body>
<h1>Welcome to XHTML</h1>
<p>This is a paragraph in XHTML.</p>
<img decoding="async" src="image.jpg" alt="Image" />
</body>
</html>
Differences Between HTML and XHTML
Syntax:
- HTML: More forgiving, allows optional closing tags, and does not require attributes to be quoted.
- XHTML: Stricter syntax, requires all tags to be closed and attributes to be quoted.
Case Sensitivity:
- HTML: Tags and attributes are not case-sensitive.
- XHTML: Tags and attributes are case-sensitive and must be written in lower case.
Error Handling:
- HTML: Browsers will attempt to render HTML even if it contains syntax errors.
- XHTML: Documents must be well-formed and follow XML rules; otherwise, they will not be rendered correctly.
Self-closing Tags:
- HTML: Self-closing tags like
<br>and<img>do not require a slash. - XHTML: Self-closing tags must include a trailing slash, e.g.,
<br />and<img src="image.jpg" alt="Image" />.
- HTML: Self-closing tags like
HTML and XHTML serve similar purposes but differ in their syntax and requirements. HTML is more lenient and widely used, while XHTML enforces stricter rules to ensure document consistency and compatibility with XML standards. Choosing between them depends on the needs of the project and the desired level of syntactical rigor.
