Better than anyone, the Instagram founders understood that the human brain has evolved to interpret images incredibly rapidly. There's a reason we have the phrase "a picture tells 1,000 words." Instagram builds a unique social service around this visual metaphor. It gives you this wonderful experience of being able to scan through many pictures and experiences. You might have a network on Facebook, or on Twitter, but the people that connect to you on Instagram are distinct and you share with them in different ways.