1. What is the difference between block-level and inline elements in HTML?

In HTML, elements are categorized as either block-level or inline, based on how they are rendered in the browser.

1. Block-level elements: These elements take up the full width available, regardless of their content, and start on a new line. Examples include <div>, <h1> to <h6>, <p>, and <section>. Block-level elements are typically used for larger sections of content.

2. Inline elements: These elements only take up as much width as necessary and do not start on a new line. Examples include <span>, <a>, <em>, and <strong>. Inline elements are usually used for smaller bits of content within block-level elements.

The key difference lies in their behavior and usage in layout. Block-level elements are used to structure the main parts of a webpage, while inline elements are used for finer-grained control over text and small content fragments.