HTML is an acronym that stands for HyperText Markup Language, which is used for creating web pages and web applications. A markup language is a computer language that is used to apply layout and formatting conventions to a text document.

The correct sequence of HTML tags to start a webpage is html, head, title, and body.

The <b> -bold tag- tag in HTML is used to display the written text in bold format.

The <h1> tag is used to insert the main heading or the highest level heading.

The <br> tag in the HTML document is used to create a line break in a text. If we place the <br> tag in HTML code, then it works the same as pressing the enter key in a word processor.

The <u> - underline tag tag in HTML is used to display the underlined text. It rendered as a solid underlined text, but it can be changed using CSS properties.

The <hr> tag is used to specify a paragraph-level thematic break in HTML document. It is called a horizontal rule and draws a horizontal line.

The id attribute is used to specify a unique id for an element of the HTML document. It allocates the unique identifier which can be used by the JavaScript and CSS to perform certain tasks.

The style attribute in HTML is used to change the style of existing HTML elements. It can be used with any HTML tag. To apply the style on the HTML tag, you should have the basic knowledge of CSS properties.

HTML programs can be read and rendered by the web browser. A web browser can support several web pages.