Why is Instagram so popular? The answer to this question is not always apparent - and it lies deeply hidden in the psyche of us normal people! I have few thoughts on this popular way of expression. As mentioned here, there are more than 300 million active monthly instagram users, with more than 75 million daily active users.
The first is that we are visually stimulated creatures. I have yet to meet a human that is not able to cast eyes on something of beauty and not appreciate it in some way or another. We appreciate, judge, obsess, love and hate objects based on the way they interact visually with our being. You will propably notice the cunning use of the term "something of beauty", since we don't always agree on what is beautiful to us. But we definitely appreciate it in similar visual ways!
The format of Instagram also challenges the age old golden triangle theorem - or it is at least a very pleasing departure from it. The format wa spropablly determined by the imnitial limitations of the mobile phone, but I think it is now an aceptable form of expressing visual art. I have seen many lively discussions and efforts to fit a vista into this format. Off course, a shiort search will also show that the landscape/portrait formats are still valid - many vistas have impact in that way.
The last thing I would like to say about Instagram, is that people like to share their lives - and the ideal way is to show an image that tells a story of a thousand words! I might be short of words if you point out Instagram accounts that specialize in selfies - one account holder stated "Sorry, I take selfies only"! Many people on Instagram tend to build a body of work that characterize them, their daily lives, and values. A great way of sharing!
I personally find that Instagram has forced me to look for the beauty in everyday things - when you are forced to look for beauty you are more inclined to appreciate the small things around you. I ran a campaign where I posted at least two images every day, for a period of six months. I met some really interesting people this way, while my appreciation of my environment went up a few steps. You should try it!