The Wikipedia Version (formerly referred to as "The Reader's Digest Version")
An ale is a private party where a number of morris sides get together
and perform dances for their own enjoyment rather than for an audience.
Food is usually supplied, and sometimes this is a formal meal known as a
feast or ale-feast. Occasionally an evening ale will be combined with a
day or weekend of dance, where all the invited sides will tour the area
and perform in public. In North America the term is widely used to
describe a full weekend of dancing involving public performances and
sometimes workshops. In the sixteenth to nineteenth centuries, the term
"ale" referred to a church- or village-sponsored event where ale or beer
was sold to raise funds. Morris dancers were often employed at such
events. - Wikipedia