HTML stands for HyperText Markup Language. It is the standard markup language used to create the structure of pages on the World Wide Web. HTML elements form the building blocks of all websites.
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CSS selectors identify which HTML elements a set of CSS rules should apply to. They can match by tag name, class, id, attributes, and more complex relationships.
Common selectors include element selectors (p), class selectors (.note), and ID selectors (#header). Pseudo-classes and combinators enable powerful targeting.
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