What is Keyword stuffing?

A technique of overusing a target keyword on a page, sometimes hiding it in white text, to manipulate early search algorithms. Google now penalizes this practice and can demote or remove offending pages from results.

From 12 Essential On-Page SEO Factors You Need To Know Ep. 541

Flooding page content with repeated keywords in an attempt to rank, which search engines register as spammy and which can result in a Panda penalty.

From The 10 Most Common SEO Mistakes by Alexander Kesler #350

Placing excessive keywords in tiny or hidden text on a page to manipulate rankings. Google can detect and ban sites for this, and competitors can report it.

From Bad Competative Analysis and Keyword Prominence Vs. Stuffing - Unknown Secrets of SEO E-Webstyle Number 14

The practice of overloading content with keywords. The episode notes Google has updated its algorithm against this, but suggests YouTube has not penalized it as heavily.

From 3 Important Search Engines to Leverage for Your Content Marketing by Rachel Lindteigen #400

Overusing keywords in content in a way that does not adhere to genuine language patterns, which search engines like Google and Bing can detect and penalize.

From Increasing SEO Visibility - #SEOpodcast 249

Placing keywords in content or meta tags in a way that does not make syntactical sense, or including keywords in the meta keyword tag that do not appear on the page, which Google can penalize.

From Google Bots and Keyword Stuffing - Unknown Secrets of SEO E-Webstyle Number 59

Placing target keywords far too frequently in page content so it becomes obvious to readers and search engines, considered a borderline black hat technique that all search engines penalize.

From Using the Microsoft SEO toolkit - Unknown Secrets of SEO E-Webstyle Number 50