I guess I should explain some for all you non-Norwegians. The 17th of May is Norway's national day (Independence Day) and it's a big celebration. I guess the most well known part is the children's parade, where all the children participate. The concept isn't really more than walking along being happy and shouting, but it's really special when everyone is so into it. Oh and marching bands of course. I love the drums ^^
I'm not really sure how old the tradition is, but I'm pretty sure it started after Norway was liberated from Germany in 1945. I'm not good at explaining, so if you want to know more just click here for the wikipedia.
The rest of the pics are from the Russ parade. Russ is what we call people who are graduating from high school. They spend the 3 weeks before May 17th wearing weird clothes, doing weird "dares" and mostly just being drunk. The teachers hate it, but I remember it as good fun ^^. But ya, they end it all with a parade as well. I could tell you more, but read the wiki instead.