In this context, prominent means: meaningful and relevant. Search engines calculate the importance of keywords on a webpage based on the position of the word in the text. The oftener the keyword occurs in the text, the more relevant it will be classified by the search engine. Therefore, take care that the keywords are included in the headlines and in the first paragraphs. Also, the positions of keywords in the link are reflected in the evaluations of the search engines again. The more at the top the keywords are the better for the ranking. However, the attractiveness of the texts must not be concerned by the keyword prominence.