If you use a <strong> tag to make the text bold it also looks bold in most browsers.it also contains on start tag and end tag. <strong></strong>
Strong Tag in HTML - It is logical tag. This means that they are used purposely when the designer wants to put strong impact for particular words or phrases. <strong> is semantic - it describes the text it surrounds; this text should be stronger than the rest of the text you've displayed.
Hoe can apply?
<p><strong>This text is strong</strong></p>
Simply strong is use for the emphasis of text in strong manner.it is better than bold.