“Collection”, this is an odd word in the Tango world. It has come to mean that we, as dancers, want to bring our feet ‘together’ in some fashion. Some people refer to this idea or concept as “closing” your feet. Meaning to close the gap that naturally exists between them from a standing position where our legs are slightly apart to create more stability in our stance. ‘Collection’ is a refined version of this idea that exists 2 primary reasons. The first is very practical. And the second is purely visual. See > https://tangotopics.com/tango-social-collection/