There are several types of URL redirects that a webmaster can implement for a URL that is temporarily or permanently unavailable. The 301 redirect indicates that the original page content has been permanently moved to another URL whereas the 302 redirect indicates the content has been moved temporarily. Both 301 and 302 redirects are implemented by the webserver. There is also an on-page technique to redirect a URL called a meta refresh, but the meta refresh causes more latency and thus is considered a poor user experience.
Learn about 301 versus 302 redirects