The Dynamic Post Filter is a filter for the frontend, where visitors can view a list of posts that is filtered by tag groups or - in a two-step filter - by tag groups and associated tags.
In order to display the Dynamic Post Filter, you insert the shortcode
into a page. Optional parameters are described here.
Your visitors will then see a pull-down menu where they can select a group. Alternatively, they can select all groups at once by clicking on the "down" symbol on the right.
With the default settings, each group has its own field to enter tags of this group. Your visitors can now select tags, and only posts that match these tags will be displayed. Depending on the parameters, however, the second step with the tags is omitted and the list of posts under the menu displays those entries, that match the selected groups. (i.e. that contain tags that are assigned to the selected groups.)
By default, a post is displayed if at least one of its tags match the selected tags in the filter (tag a OR tag b OR tag c OR ...). You can also change it with the parameter "operator" and display post that contain all of the selected tags (tag a AND tag b AND tag c AND ...).
A special operator is "IN AND": Matching posts will have at least one tag among the tags of each group. In that case, the post list is empty, if for any group no tag matches the tags of that post.
You can see the Dynamic Post Filter in operation on the demo site.