HTML (HyperText Markup Language) is the standard markup language for creating web pages. It describes the structure of a web page and consists of a series of elements that tell the browser how to display the content.

HTML elements are the building blocks of HTML pages. They are represented by tags, such as <h1> for headings, <p> for paragraphs, and <a> for links.

• <h1> to <h6>: Heading tags
• <p>: Paragraph tag
• <a>: Anchor (link) tag

Attributes provide additional information about HTML elements. They are always included in the opening tag and usually come in name/value pairs like name="value".

• href: Specifies the URL of a link
• src: Specifies the source of an image
• alt: Provides alternative text for an image

HTML forms are used to collect user input. They contain form elements like text fields, checkboxes, radio buttons, and submit buttons.

• <input>: Input field
• <textarea>: Multi-line text input
• <button>: Button

Semantic HTML introduces meaning to the web page rather than just presentation. Examples include <header>, <footer>, <article>, and <section>.