Keywords or tags are very important because they help you to have a higher page rank in the Google Search Engine. This means that with a proper use of keywords you can have your hub or webpage even among the first ten listed by Google Search Engine when someone types in the keywords (you used) in the search box. The best way to use keywords is to put them in the title, at the beginning of the text once, twice or more in the body of the text (depends on the word count of the whole text) and once at the end. Simply said, these words help your hub to be found by other people doing (re)search on Google or elswhere.
Nevertheless, if there are many online articles on the same topic you used, Google will list those which provide the best info about this topic first and those that have the best links and backlinks to related topics!