Today is the astronomical northern solstice. In its honor there will be some astronomical (huge) parties.
Midsummer is not a big deal here, far below the 50th parallel, but it's huge in Scandinavia where winters are long, cold and very dark.
This is winter's antithesis, all light and warmth, the longest day celebrated since pagan times.
When Christianity arrived in Northern Europe the Church added the Nativity of St. John the Baptist on this date so the partying is legitimate for everyone with festivals, bonfires, feasting, singing, and dancing 'round the maypole.
And don't forget the theatricals. You may know today's name -- even though we don't celebrate it -- from Shakespeare's A Midsummer Night's Dream.
So as you note the solstice at exactly 7:09pm (EDT) you might call it the "beginning of summer" but it's Midsummer to those in the know.
(photo from Shutterstock)