[SEO]

Content quality guidelines

Content quality guidelines (from Yahoo Help):
"At Yahoo, we’re focused on delivering the Web’s best search experience, full of relevant, high-quality content. The Yahoo Search Content Quality Guidelines are designed to help make sure that poor-quality pages don’t degrade the Yahoo Search experience.

High-quality content
These are the kind of webpages Yahoo wants to include in its search results.

Original and unique content of genuine value.
Pages designed primarily for people, where search engine considerations are a secondary concern.
Hyperlinks intended to help people find interesting, related content.
Metadata (including title and description) that accurately describes the contents of a webpage.
Low-quality content
These are the types of content that Yahoo does not want included in search results.

Basics
Content that harms the accuracy, diversity, or relevance of search results.
Pages using methods to artificially inflate search engine ranking.
Multiple websites or webpages offering substantially the same content.
Webpages produced in great quantities, which have been automatically generated or which are of little value (cookie-cutter pages).
Misuse of competitor names.
Webpages that seem deceptive, fraudulent, or provide a poor user experience.
Specific problems
Websites with numerous, unnecessary virtual hostnames.
The use of text or links that are hidden from the user.
Websites excessively cross-linked with other sites to inflate a site's apparent popularity (link schemes).
Pages built primarily for search engines or webpages with excessive or off-topic keywords.
Websites that give search engines different content than what the end user sees (cloaking).
Pages dedicated to redirecting the user to another page (doorway pages).
Websites that use excessive pop-ups that interfere with user navigation."

Source: https://help.yahoo.com/kb/search-content-quality-guidelines-sln2245.html.