If you are going to quote something in normal writing you place speech marks (double quotes) around it.  That is also fine on the Web.  However, if you want to style the text in a way to show that it is a quotation you can put tags around it.

Short quotes

Just place <q> and </q> where the quotation marks would have been.  The browser will place the quotation marks there as it knows it is a quote.  For example paste this into a new page called quotes.html:

<p>The man shouted "No!" but the dog still said <q>Woof</q> and ran away.</p>

The two quotations may look slightly different depending on your browser.  The big difference though is that you can use the q element and CSS to make all quotations look slightly different in terms of colour, font or other styling.

Note that q is for in-line quotations which are normally just a few words inside a paragraph.

Long quotes

If you want a long quotation displayed separately then use blockquote.  Under the previous paragraph in quotes.html paste this:

<blockquote cite="https://w3c.github.io/html/grouping-content.html#the-blockquote-element">The blockquote element represents content that is quoted from another source, optionally with a citation which must be within a footer or cite element, and optionally with in-line changes such as annotations and abbreviations.</blockquote>

Depending on your browser the quote should look a little different from normal paragraphs.

The cite attribute in the code above provides a URL where the quote comes from but is not intended for the user.  It allows the browser and search engines to know where the quote came from.

If you want to visually tell the user where the quote is from add a cite element (as well as the cite attribute) to the blockquote:

<blockquote cite="https://w3c.github.io/html/grouping-content.html#the-blockquote-element">The blockquote element represents content that is quoted from another source, optionally with a citation which must be within a footer or cite element, and optionally with in-line changes such as annotations and abbreviations.<cite>W3C</cite></blockquote>

You could also make the citation a link if you want the user to be able to go to the original page.

In-line and block quotes complete with citation