What are the purposes of the tags in HTML?

Question

<p></p>

Answer 1

it displays the text written in it.
some attributes are also there like alignment and colours.

Answer 2

The tags help structuring the content by specifying what "type" of content it is
e.g..
title, paragraph of text, element of a list, cell of a table etc...
The browser interprets the html and display content with applying some default style according to the tag and tag attributes.
(Then, optionally, the style can be further modified by applying CSS style)