The World of the Fae - Seelie and Unseelie Courts

If you are a fan of Fae books you have no doubt heard the terms Seelie and Unseelie. But what do they mean? In Scottish folklore, Seelie means light fairy and Unseelie means dark fairy. The Seelie Fae were said to work with humans and help them. The word Seelie means happy or peace in Gaelic. Certain types of Fae are said to reside in the Seelie world including brownies and elves. 
The Unseelie Fae are said to be the bad or evil fairies and they include redcaps, hags and those who were wicked in life. They tend to attack humans or cause chaos. 
The concept of Seelie and Unseelie is quite common in a lot of Fae based books and in role playing games. 
The Fae are varied, magical and there are so many tales and stories to take from that you can create entire worlds based around them. 
Did you know that during Beltane (May 1st) the veil between our world and the Fae world is at its thinnest? Many people will decorate their garden, put out offerings and take walks in nature during this time. It may be the 21st Century, but Fae lore is still fascinating to us. 
What is your favorite type of Fae?