Joking aside about your fridge and piano, Internet of Things connects everyday devices together, often via the internet. Example of this might be car parks that 'know' when they're full, or can show you where free spaces are, to litter bins that can tell you how full they are. Less extreme examples are the ability to control your heating from your mobile (anywhere in the world), and my cat door that can tell me when my cat comes in and goes out.
Initial reactions can be that this is all rather superficial. However, there are many benefits:
We have worked on a number of IoT projects. Probably the largest is a fully robotic laboratory for BP, allowing polymer chemists to set up catalyst experiments online, and have those experiments run automatically, and have the results returned by email. We are currently working on a control system for an anaerobic digester which converts farm waste into electricity, and a beehive monitor that can tell you the environment inside a beehive from anywhere in the world.