Often it is valuable to summarise the content of a web page or article and outline the most common keywords. This can be useful in categorising articles but it would require the author to indicate which keywords are appropriate.
This could be a poor strategy as some authors will not want to take the time to do this and others could use false keywords as a form of spam not related to the article content.
Fortunately there is a PHP class that will allow a site owner to create automatic tag clouds or article summaries for their site. Use of software will save time and improve accuracy.
This PHP class, written by Ver Pangonilo from the Philippines analyzes the article text and determines keywords based on the frequency of one or multiple words. You can influence the outcome by providing the parameters you want to filter by: