A 301 redirect is a permanent redirect from one URL to another.  301 redirects send site visitors and search engines to a different URL than the one they originally typed into their browser or selected from a search engine results page.

These redirects also link various URLs under one umbrella so search engines rank all of the addresses based on the domain authority from inbound links. 

Refer: https://blog.hubspot.com/blog/tabid/6307/bid/7430/what-is-a-301-redirect-and-why-should-you-care.aspx