These are, as the name suggests, the tibetan prayer flags. They are usually set along mountain ridges as It is believed that the prayers will be blown by the wind to spread the good will and compassion into all pervading space. They are thought to bring benefit to all. I took this photo on top of Stawamus Chief (or just chief) in Squamish. To be more precise on top of the third peak, the highest section of the chief.