Redirect Glossary

Redirects are simple in concept — send the browser somewhere else — but the terminology gets dense fast. This glossary covers every term you will encounter when working with URL redirects, from HTTP status codes to implementation methods to failure modes.

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HTTP Redirect Status Codes

301 Moved Permanently

The URL has permanently moved to a new location. Search engines transfer link equity (ranking power) to the new URL. Browsers cache 301 redirects aggressively, sometimes indefinitely.

Use for: permanent URL changes, domain migrations, HTTPS upgrades, slug changes.

302 Found (Temporary Redirect)

The URL is temporarily available at a different location. Search engines generally keep the original URL indexed. Browsers do not cache 302s as aggressively as 301s.

Use for: A/B testing, geo-routing, temporary maintenance pages. In practice, many developers use 302 when they mean 301. This is a common mistake.

303 See Other

Tells the client to retrieve the resource at a different URL using a GET request, regardless of the original request method. Introduced in HTTP/1.1 to clarify behavior that 302 handled ambiguously.

Use for: redirecting after a POST form submission (Post/Redirect/Get pattern).

307 Temporary Redirect

Like 302, but the client must use the same HTTP method for the redirected request. If the original request was POST, the redirect must also be POST.

Use for: temporary redirects where preserving the request method matters (API endpoints, form submissions).

308 Permanent Redirect

Like 301, but the client must use the same HTTP method. The permanent counterpart to 307.

Use for: permanent redirects of non-GET endpoints (APIs, webhooks) where the method must be preserved.

Redirect Concepts

Redirect Chain

A sequence of multiple redirects between the initial URL and the final destination. Example: A redirects to B, B redirects to C, C returns 200. That is a three-hop chain.

Each hop adds latency (typically 50-200ms) and dilutes SEO link equity. Flatten chains wherever possible — redirect A directly to C.

Redirect Loop

A circular redirect where URL A redirects to URL B, and URL B redirects back to URL A (or through a longer cycle that eventually returns to A). The browser gives up after a set number of hops and displays ERR_TOO_MANY_REDIRECTS.

Common causes: misconfigured CMS settings, conflicting server rules, SSL/TLS mode mismatches with CDNs like Cloudflare.

Hop

A single redirect in a chain. A redirect from A to B is one hop. A chain from A to B to C is two hops. Fewer hops is always better.

Canonical URL

The preferred version of a URL when multiple URLs serve the same or similar content. Defined via the <link rel="canonical"> tag or HTTP Link header. Redirects and canonical tags should agree — if you redirect A to B, B's canonical should point to itself, not back to A.

HSTS (HTTP Strict Transport Security)

An HTTP response header (Strict-Transport-Security) that tells browsers to always use HTTPS for a domain. Once a browser receives an HSTS header, it internally redirects HTTP to HTTPS (a "307 Internal Redirect") without ever contacting the server over HTTP.

This eliminates one redirect hop for repeat visitors. HSTS preload lists eliminate it for first-time visitors too.

URL Forwarding

A general term for sending traffic from one URL to another. Often used by domain registrars for simple domain-to-domain redirects. Technically, URL forwarding is implemented via HTTP redirects (usually 301 or 302).

Redirect Implementation Methods

Server-Side Redirect

A redirect issued by the web server before any page content is sent to the browser. This includes redirects from Apache (.htaccess), Nginx (return or rewrite), Cloudflare (Page Rules, Bulk Redirects), and application framework redirects (Express, Django, Rails, Next.js).

Server-side redirects are the fastest and most SEO-friendly type. The browser receives a 3xx status code and a Location header, then immediately requests the new URL.

Client-Side Redirect

A redirect triggered by code that runs in the browser — either HTML <meta> tags or JavaScript. The browser loads the initial page first, then navigates to the new URL after parsing and executing the code.

Client-side redirects are slower than server-side redirects and are not reliably followed by all search engine crawlers.

Meta Refresh

An HTML tag that tells the browser to navigate to a new URL after a delay:

<meta http-equiv="refresh" content="0;url=https://example.com/new-page">

A delay of 0 makes it as fast as possible, but it is still slower than a server-side redirect because the browser must first download and parse the HTML. Search engines may or may not pass link equity through meta refreshes.

Use for: static HTML pages where you have no server-side control. Avoid everywhere else.

JavaScript Redirect

A redirect implemented via JavaScript, typically using window.location.href, window.location.replace(), or framework-specific routing.

window.location.replace("https://example.com/new-page");

Even slower than meta refresh because the browser must download, parse, and execute JavaScript. Search engines may not follow JavaScript redirects at all.

Use for: conditional redirects based on client-side logic (device detection, cookie state). Never use as a substitute for server-side redirects.

Security Terms

Open Redirect

A vulnerability where a URL on your domain accepts a user-supplied destination and redirects to it without validation. Example:

https://yoursite.com/redirect?url=https://evil-site.com

Attackers use open redirects for phishing — the link looks like it goes to your trusted domain. Always validate redirect destinations against an allowlist.

Redirect Validation

The process of checking that a redirect target is safe and expected. For user-supplied redirect URLs, this means verifying the destination is on an approved domain and path. Never redirect to arbitrary external URLs based on query parameters.

SEO Terms

Link Equity (Link Juice)

The ranking value passed from one page to another through links and redirects. 301 redirects pass most link equity. 302 redirects may or may not pass equity depending on search engine interpretation. Redirect chains dilute equity with each hop.

Crawl Budget

The number of pages a search engine will crawl on your site in a given period. Redirect chains waste crawl budget — the bot has to follow multiple hops instead of reaching content directly. For large sites, this matters.

Soft 404

A page that returns a 200 status code but displays a "not found" or error message. This is not a redirect issue directly, but redirects that land on soft 404 pages are effectively broken — the user reaches a dead end with a misleading status code.

Failure Modes

ERR_TOO_MANY_REDIRECTS

A browser error displayed when a redirect loop is detected. Browsers typically give up after 20-30 redirect hops. Fix the loop by tracing the redirect chain and finding the circular reference.

Broken Redirect

A redirect that points to a URL that returns a 4xx or 5xx error. The redirect itself works, but the destination is dead. Common after site migrations when redirect targets are not updated.

Redirect Decay

The gradual degradation of redirect rules over time as sites evolve. Pages move again, paths change, and old redirects point to intermediate URLs that now redirect elsewhere. Regular audits catch redirect decay before chains get long.

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Know the words, and you will understand the problem. Understand the problem, and you can fix it.