Instagram has over 800 million global users who can share photos and videos. It was created in 2010 by Kevin Systrom and Mike Kroeger and acquired by Facebook in 2012 for $1 billion. There are several reasons why people may follow others on Instagram, such as wanting more followers themselves or mistaken identity due to similar usernames or profile pictures. The document discusses two methods - mSpy and Spyzie apps - that allow tracking another's Instagram activity and monitoring messages, calls, location and other app activity by installing the app secretly on the target device.