Index gate
SEOA rule that keeps a generated page out of search indexes until it holds enough content to be worth landing on, most often a minimum number of listings.
SEO
Canonical URL
The single preferred address for a piece of content, declared with a link rel=canonical tag so search engines consolidate duplicates onto one page.
Also called rel=canonical, canonicalization
A canonical URL is the address you want a search engine to treat as authoritative when the same content is reachable at more than one address. It is declared with <link rel="canonical" href="..."> in the page head and is a strong hint rather than a directive.
Duplicates are easy to create without noticing. Query parameters for filters, sorts and tracking; trailing-slash and non-trailing-slash variants; www and apex versions; HTTP and HTTPS; pagination; and session or referral parameters all produce distinct URLs serving substantially the same content.
The rules that keep this clean. Every page carries a self-referencing canonical pointing at its own clean URL. Filter and sort permutations either canonicalize to the unfiltered page or are noindexed, since the alternative is a combinatorial explosion of near-identical pages. Redirect one host variant to the other with a 301 and pick one trailing-slash convention sitewide.
On a directory this matters most on faceted pages, where a category page crossed with three filters and two sort orders can generate dozens of URLs for one set of listings.
Last reviewed .
See also
Programmatic SEO
SEOGenerating many pages from a single template and a structured data source, so each combination of values becomes its own indexable page targeting a specific query.
Meta description
SEOThe page summary in a meta tag, used by search engines as the snippet under a result. Not a ranking factor, and a strong influence on whether anyone clicks.