Who is Glinda the Good from The Wonderful Wizard of Oz and what is their importance?

Glinda is the Witch of the South. She is beautiful and filled with kindness. When Dorothy enters Glinda's kingdom, Glinda asks her for the Golden Hat, which she will use to make sure Dorothy's friends are taken home, as well as grant the monkeys their freedom. Glinda is also the one who tells Dorothy how to get home.