Use the slider or type a value to change the setting if you have a specific reason to do so.
rare
With this setting, the tool will focus on words which are rare or unusual in general language or in the reference corpus. This setting is generally most useful, especially for terminology.
common
With this setting, the tool will focus on words which are very frequent in general language or in the reference corpus. This setting can be useful, for example, when comparing the use of common words in two literary texts.
In either case, the tool will produce a list of words which appear more frequently in the focus corpus (or subcorpus) than in the reference corpus (or subcorpus). Changing this setting only makes the tool focus on different parts of the word frequency list.