Litha is the Summer solstice here in the Northern Hemisphere. This year it falls on Sunday, June 21st. On this date the Sun reaches its zenith in the sky. It is the longest day of the year, and the point at which the Sun seems to just hang there without moving – in fact, the word “solstice” is from the Latin word solstitium, which literally translates to “Sun stands still.”

The travels of the sun were marked and recorded. Stone circles such as Stonehenge were oriented to highlight the rising of the sun on the day of the Summer Solstice.

Interestingly, there's always been a question about whether or not Midsummer was truly celebrated by the ancients. While there's scholarly evidence to indicate that it was indeed observed, there were suggestions made by Gerald Gardner, the founder of modern Wicca, that the solar festivals (the solstices and equinoxes) were actually added later and imported from the Middle East. Regardless of the origins, many modern Wiccans and Pagans do choose to celebrate Litha every year in June.

In some traditions, Litha is a time at which there is a battle between light and dark. The Oak King is seen as the ruler of the year between winter solstice and summer solstice, and the Holly King from summer to winter. At each solstice they battle for power, and while the Oak King may be in charge of things at the beginning of June, by the end of Midsummer he is defeated by the Holly King.

This is a time of year of brightness and warmth. Crops are growing in their fields with the heat of the sun, but may require water to keep them alive. The power of the sun at Midsummer is at its most potent, and the earth is fertile with the bounty of growing life.

Source: About.com