The moon has a great deal of importance within Wicca.
The Triple Moon
The triple moon is often represented by the symbol )0( which some Wiccan's will claim represents the three phases of the moon. The only problem with his is that the moon actually has four phases - Full Moon, Waxing, Waning and New Moon. You could still interpret the symbol as representing the four phases of the moon in that the other (dark) halves of the crescents could be used to symbolise the New Moon.
Full Moon Magick / Esbats
Apart from the coven gatherings around the eight Solar Festivals, known as Sabbats, a coven will also meet for other purposes once a month. This is most likely to be on a Full Moon and the rituals will be focused more on training, psychism and healing.
The magick and rituals performed at the full moon will be centred around the concepts of completion and fruition.
Waxing Moon Magick
The Waxing Moon is a time at which spells and rituals pertaining to attraction would be performed. It would also be a time for working on increasing and growing aspects.
Waning Moon Magick
As you might have already guessed, the waning moon is a time when rituals and spells would be directed towards decreasing or lessening. This would also be a time when you might focus on things you wish to banish or get rid of.
New Moon Magick
The New Moon brings about a time of starting afresh and new beginnings.
Half Moon
When the moon is at exactly half, whether in the waxing or waning phase, this can be an excellent time for doing balancing work.
Blue Moon
A Blue Moon occurs when we see two full moons falling in the same month, where the second moon is considered to be the Blue Moon. It does not actually turn the colour blue, although there are some circumstances which can sometimes cause this to happen. It is a very powerful time at which to do magick, especially when you really need a spell or ritual to work well.
Lunar Eclipse
A lunar eclipse has always been associated with destruction, as both solar and lunar eclipses were often viewed with great fear. They have therefore become considered a potent time to do banishings and other activities similar to what would be done during a waning moon.
Celtic Lunar Calendar
The celts ascribed a particular tree to each month of their lunar-based calendar. The calendar starts on the first new moon after Yule and cycles through the list below. These can be used for inspiration as to the focus of esbat rituals. The following is a general guide to them as found in "Circle of Fire" by Sorita D'Este and David Rankine
1. Birch - Cleansing and New Beginnings
2. Rown - Protection against magick, control of the senses
3. Alder - Prophecy, spiritual protection
4. Willow - Feminine, lunar rhythms, fertility
5. Ash - Passage between inner and outer worlds
6. Hawthorne - Cleansing, Chastity, Protection, restraint
7. Oak - Solid protection, doorway to the mysteries, strength
8. Holly - Victory, fatherhood, vigour
9. Hazel - Intuition, wisdom, poetry, divination, inspiration
10. Apple - Beauty, wisdom, choice, immortality
11. Vine - Prophecy, letting go of inhibitions, instinct, emotions
12. Ivy - spiral of the self and inner journey, transformation
13. Reed - Direct action, searching out basic truths