22. The non-transitory computer readable storage medium of claim 21 , wherein generating the first metadata item based upon the text comprises: using a stemming method to generate a stem word based upon the text; and generating the first metadata item based upon the stem word.
21. The non-transitory computer readable storage medium of claim 20 , wherein generating the first metadata item comprises: extracting text from the activity history; and generating the first metadata item based upon the text.