A solstice is not a day. It is the time that the Sun reaches it's most northern (summer) or southern (winter) point. The Sun is directly overhead of the Tropic of Cancer in the Northern Hemisphere during the Summer Solstice.
The Summer Solstice was at 6:39 AM Eastern Daylight Time, or 9:39 AM Pacific Daylight Time where I live.
Summer Solstice means that if you live north of the Arctic Circle (66°33′45.8″ degrees latitude) you will have at least one day of permanent sunshine. The city of Fairbanks, Alaska is at 64°50′37 degrees latitude (less than 120 miles south of the Arctic Circle) and will have about 23 hours of daylight today.
For some reason, pagans like to dance at Stonehenge today. Not quite sure why. As if an astrological event can affect people's lives on Earth.
People mistakenly called the day of the Summer Solstice "the longest day of the year" when what they mean is it's the longest daylight of the year. Where I live, sunrise was at 5:01 this morning and sunset will be at 8:56 this evening. That's 15 hours and 55 minutes of the sun being up (if my math is correct).
When someone says "It's the longest day of the year" I usually add sardonically "Yep, 25 hours."
So enjoy the "longest day of the year." Pretty soon (well, six months) we'll have the shortest day of the year, the Winter Solstice.