I do realize it's not a big deal in many other places but here in Scandinavia it's as important as christmas, or in some cases more important then christmas.
It's a celibration that dates back to the vikings and probebly even longer. The scandinavian countries (apart from maybe denmark) are covered in darkness most of the year so the extra hours of light is celebrated in the summer, and midsommar is as the english word the middle of the summer and the lightest day of the year
Where I live, the sun sets at around 10:30 PM and raises over the horizon again at 4 am (around 18 hours of daylight). In the winter we get only around 5 hours of daylight
It's actually so important in Sweden that when our nationalday was introduced it was considered to be celebrated on Midsommar even if it had nothing to do with our independence or anything of Swedens history as a country but it got it's own day.
The church even tried to ban it around the 1400 but failed miserably
