Last week, I reported that Yahoo dropped the meta keywords tag and stopped using it completely. Remember, I told you that I wasn't convinced when I heard that and I asked the Senior Director of Search at Yahoo if he was sure? Well, he said he was, but in reality, he was mistaken.
Danny and others have confirmed that Yahoo is still using the meta keywords tag when ranking. People have set up test sites that show this to be the case. Danny received an official statement from Yahoo on how they use this meta keywords tag, which they do use:
What changed with Yahoo’s ranking algorithms is that while we still index the meta keyword tag, the ranking importance given to meta keyword tags receives the lowest ranking signal in our system.
Words that appear in any other part of documents, including the body, title, description, anchor text etc., will take priority in ranking the document – the re-occurrence of these words in the meta keyword tag will not help in boosting the signal for these words. Therefore, keyword stuffing in the keyword tag will not help a page’s recall or ranking, it will actually have less effect than introducing those same words in the body of the document, or any other section.
However, when no other ranking signal is present, unique words that only appear in the meta keyword tag section of documents can still be used to recall these documents.
I am not sure why I didn't originally believe it. It was not like I had proof at the time. In any event, we are all human and we make mistakes. Search representatives are often seen as the single authority on SEO related questions, but in reality, they cannot know everything and are human, like you and me.
Forum discussion continued at WebmasterWorld.