Why Instagram Matters to Marketing [Infographic]
This infographic nicely summarizes the stats around users, engagement, growth, top brands, hashtags, and posting best practices.
Fun fact #1: 90% of Instagram users are under 35.
Fun fact #2: Best days to post are Mondays and Thursdays - and never ever under any circumstance should you post between 3 and 4 pm on any day. Not sure why.