what is the use of <nav> tag?

Answer 1

<nav> = Navigation . for create menu (like <div class="navigatin">...</div>)

Answer 2

The <nav> tag defines a set of navigation links.

Notice that NOT all links of a document should be inside a <nav> element. The <nav> element is intended only for major block of navigation links.

Browsers, such as screen readers for disabled users, can use this element to determine whether to omit the initial rendering of this content.

source : http://www.w3schools.com/tags/tag_nav.asp

Answer 3

It is used to create menus