There’s a whole galaxy of connected items you can buy to ostensibly make your life easier: speakers, locks, coffee mugs, even dog collars. The so-called “internet of things” is already big and growing fast. By 2021, the market for all things connected is on track to pass $500 billion. There is no upfront connection or service fee to make these things work; we pay for them with our data. The Economist’s technology editor, Tim Cross, walks us through privacy concerns, security concerns and 5G.