- To track clicks and impressions and log referring pages.
- To indicate the new location of a resource that has moved.
- To add a trailing slash to URL directory names to make their contents accessible to the browser.
- To reserve multiple domains, allow for "user-friendly" or "vanity" domains and URLs, and catch misspelled/mistyped URLs.
- To connect between different parts of a site or application, different country-code top-level domains, different protocols (HTTP to HTTPS), different security policies (e.g. unauthenticated and authenticated pages) etc.
Redirects trigger an additional HTTP request-response cycle and add round-trip-time latency.
It's important to minimize the number of redirects issued by your application - especially for resources needed for starting up your homepage. The best way to do this is to restrict your use of redirects to only those cases where it's absolutely technically necessary, and to find other solutions where it's not.