According to 4.9 Billion Reasons To Celebrate World IoT Day 2015 article April 9th is the 5th annual World IoT Day. World IoT Day aims to be a worldwide event bringing together Makers, entrepreneurs, industry leaders, and citizens to discuss, design and develop the emerging Internet of Things. A full calendar of events can be seen at: iotday.org/
By the end of 2015, Gartner estimates that 4.9 billion connected things will be in use. If you are still wondering on what IoT is and how you could use it, check What Exactly Is The “Internet of Things”? graphic primer behind the term & technologies.