At the point of the summer solstice in the Northern Hemisphere the sun appears to be directly overhead at midday along an imaginary line on the Northern Hemisphere at latitude 23.45 deg N known as the Tropic of Cancer. At the summer solstice in the Southern Hemisphere the sun appears directly overhead at midday along an imaginary line 23.45 deg S known as the Tropic of Capricorn. These two lines were so-called because, in ancient times when the first Western astrological charts were set, the sun rose in these constellations at these times.
These lines mark the southern and northern most points where the sun can appear to be directly overhead to an Earth-based observer, and encompass the tropical region of the earth's surface.
The term summer "solstice" is of Middle English etymology, from Old French, from Latin solstitium, from sol sun + -stit-, -stes standing; akin to Latin stare to stand. Terms such as vernal equinox, and autumnal equinox are also of latin origin; having originally referred to northern hemisphere seasons.
Midsummer is the time around the summer solstice. There are traditional holidays celebrated in Northern Europe and elsewhere at this time. In Denmark and Norway midsummers eve is known as Sankt Hans Aften. Bonfires are lit on beaches throughout the land as darkness comes and effigies and fireworks are thrown into the fires.
Summer Solstice is also celebrated as a Wiccan sabbat, called Litha. Every year, a celebration takes place at Stonehenge.
In the USA, Canada, and some other countries, the summer solstice is regarded as the start of summer. In other countries, including Ireland, China, and Japan, the summer solstice is regarded as midsummer. For example, in Ireland, summer begins on May 1. Similarly, traditional East Asian calendars refers to the summer solstice as the "extreme of summer" and not the start. The Slavs celebrate the shortest night of the year as St. John's Night.