Today marks the summer solstice, the official 'start' of summer, where the sunn if at the highest point in the sky for the year. Literally comes from the Latin sol (sun) sistit (stands still).
One of the most importnat dates in the Pagan/Wican calendar. If you want to find out a little more about this look
Of course if you live in the soutern hemisphere it will be the winter solstice for you.