Here is an excerp from Wikipedia on Lindy Exchanges. I think it sums it up nicely…

"A lindy exchange is a gathering of lindy hop dancers in one city for several days to experience the dance venues and styles of that local community, and to dance with visitors and locals alike. Travelling for exchanges has contributed to the development of a global or international lindy hop community. Although the focus of lindy exchanges is on lindy hop, related swing dances such balboa, charleston, blues dance, and collegiate shag are common at 'lindy' exchanges as well, and 'exchanges' targeting these other dance styles specifically have also been organised. The term 'exchange' is derived from school or university 'exchange' programs, where students travel to another country or city to experience the local culture. Exchange students often 'swap' or exchange their own home or place at their home university with another traveller. Visitors at lindy exchanges are often hosted by local dancers, staying in their homes for the duration of the event. Lindy exchanges typically do not have lessons or workshops since the focus is on social dancing."