While the unofficial start of summer is Memorial Day, the official start of summer is the solstice. The word solstice can throw you off a bit, but just remember the official start of summer is really just the end to late sunsets. It's an amazingly slow process, but we will go from a sunset around 8:29 pm to 6:17 pm in only 4 months. Before you know it, evening practices will have to end by 5:30 pm and big jackets will begin to make their first appearances.
The first day of summer has always been accompanied by big parties and bonfires. In fact, some of the earliest accounts of celebrations go back several thousand years. From Asia to the more familial Stone Hedge, the human race has always grabbed a flame, musical instruments, and maybe a couple marshmallows or two to help bring in the season. I can only assume the sun is the only thing standing still on this day (the word solstice is Latin for "sun" and "stands still").
As mentioned in the video, due to the tilt of the earth, the north pole receives 24 hours of sunlight for 6 months and then is shrouded in darkness for 24 hours for another 6 months. That's one extreme and the equator makes up the other. Along the equator they receive a more reasonable 12 hours of sunlight through the entire year. In between the two extremes you have us! Our days vary by about 2 hours throughout the year meaning our latest sunset comes in at 8:28 (last night) and the earliest 5:06 pm (winter).